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• Webbrowser control: Get element value and store it into a variable.

  - by Khou

  Winform: Web browser Control The web browser has the following displayed content, within a html table. [Element] [Value] Name John Smith Email [email protected] For the example above, the html code, might look something like this <table> <tbody> <tr> <td><label class="label">Name</label></td> <td class="normaltext">John Smith</td> </tr> <tr> <td><label class="label">Email</label></td> <td><span class="normaltext">[email protected]</span></td> </tr> </tr> </tbody> </table> . I want to get the element value, the value to the right of the label. What is the best way to do this? .

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• How to use webbrowser control DocumentCompleted event in C# ?

  - by Margus

  Before starting writing this question, i was trying to solve following // 1. navigate to page // 2. wait until page is downloaded // 3. read and write some data from/to iframe // 4. submit (post) form The problem was, that if a iframe exists on a web page, DocumentCompleted event would get fired more then once (after each document has been completed). It was highly likely that program would have tried to read data from DOM that was not completed and naturally - fail. But suddenly while writing this question 'What if' monster inspired me, and i fix'ed the problem, that i was trying to solve. As i failed Google'ing this, i thought it would be nice to post it here. private int iframe_counter = 1; // needs to be 1, to pass DCF test public bool isLazyMan = default(bool); /// <summary> /// LOCK to stop inspecting DOM before DCF /// </summary> public void waitPolice() { while (isLazyMan) Application.DoEvents(); } private void webBrowser1_Navigating(object sender, WebBrowserNavigatingEventArgs e) { if(!e.TargetFrameName.Equals("")) iframe_counter --; isLazyMan = true; } private void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) { if (!((WebBrowser)sender).Document.Url.Equals(e.Url)) iframe_counter++; if (((WebBrowser)sender).Document.Window.Frames.Count <= iframe_counter) {//DCF test DocumentCompletedFully((WebBrowser)sender,e); isLazyMan = false; } } private void DocumentCompletedFully(WebBrowser sender, WebBrowserDocumentCompletedEventArgs e){ //code here } For now at least, my 5m hack seems to be working fine. Maybe i am really failing at querying google or MSDN, but i can not find: "How to use webbrowser control DocumentCompleted event in C# ?"

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• Cocoa threading question.

  - by Steve918

  I would like to implement an observer pattern in Objective-C where the observer implements an interface similar to SKPaymentTransactionObserver and the observable class just extends my base observable. My observable class looks something like what is below. Notice I'm making copies of the observers before enumeration to avoid throwing an exception . I've tried adding an NSLock around add observers and notify observers, but I run into a deadlock. What would be the proper way to handle concurrency when observers are being added as notifications are being sent? @implementation Observable -(void)notifyObservers:(SEL)selector { @synchronized(self) { NSSet* observer_copy = [observers copy]; for (id observer in observer_copy) { if([observer respondsToSelector: selector]) { [observer performSelector: selector]; } } [observer_copy release]; } } -(void)notifyObservers:(SEL)selector withObject:(id)arg1 withObject:(id)arg2 { @synchronized(self) { NSSet* observer_copy = [observers copy]; for (id observer in observer_copy) { if([observer respondsToSelector: selector]) { [observer performSelector: selector withObject: arg1 withObject: arg2]; } } [observer_copy release]; } } -(void)addObserver:(id)observer { @synchronized(self) { [observers addObject: observer]; } } -(void)removeObserver:(id)observer { @synchronized(self) { [observers removeObject: observer]; } }

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• Concurrent cartesian product algorithm in Clojure

  - by jqno

  Is there a good algorithm to calculate the cartesian product of three seqs concurrently in Clojure? I'm working on a small hobby project in Clojure, mainly as a means to learn the language, and its concurrency features. In my project, I need to calculate the cartesian product of three seqs (and do something with the results). I found the cartesian-product function in clojure.contrib.combinatorics, which works pretty well. However, the calculation of the cartesian product turns out to be the bottleneck of the program. Therefore, I'd like to perform the calculation concurrently. Now, for the map function, there's a convenient pmap alternative that magically makes the thing concurrent. Which is cool :). Unfortunately, such a thing doesn't exist for cartesian-product. I've looked at the source code, but I can't find an easy way to make it concurrent myself. Also, I've tried to implement an algorithm myself using map, but I guess my algorithmic skills aren't what they used to be. I managed to come up with something ugly for two seqs, but three was definitely a bridge too far. So, does anyone know of an algorithm that's already concurrent, or one that I can parallelize myself?

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• Recursively adding threads to a Java thread pool

  - by Leith

  I am working on a tutorial for my Java concurrency course. The objective is to use thread pools to compute prime numbers in parallel. The design is based on the Sieve of Eratosthenes. It has an array of n bools, where n is the largest integer you are checking, and each element in the array represents one integer. True is prime, false is non prime, and the array is initially all true. A thread pool is used with a fixed number of threads (we are supposed to experiment with the number of threads in the pool and observe the performance). A thread is given a integer multiple to process. The thread then finds the first true element in the array that is not a multiple of thread's integer. The thread then creates a new thread on the thread pool which is given the found number. After a new thread is formed, the existing thread then continues to set all multiples of it's integer in the array to false. The main program thread starts the first thread with the integer '2', and then waits for all spawned threads to finish. It then spits out the prime numbers and the time taken to compute. The issue I have is that the more threads there are in the thread pool, the slower it takes with 1 thread being the fastest. It should be getting faster not slower! All the stuff on the internet about Java thread pools create n worker threads the main thread then wait for all threads to finish. The method I use is recursive as a worker can spawn more worker threads. I would like to know what is going wrong, and if Java thread pools can be used recursively.

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• How are you taking advantage of Multicore?

  - by tgamblin

  As someone in the world of HPC who came from the world of enterprise web development, I'm always curious to see how developers back in the "real world" are taking advantage of parallel computing. This is much more relevant now that all chips are going multicore, and it'll be even more relevant when there are thousands of cores on a chip instead of just a few. My questions are: How does this affect your software roadmap? I'm particularly interested in real stories about how multicore is affecting different software domains, so specify what kind of development you do in your answer (e.g. server side, client-side apps, scientific computing, etc). What are you doing with your existing code to take advantage of multicore machines, and what challenges have you faced? Are you using OpenMP, Erlang, Haskell, CUDA, TBB, UPC or something else? What do you plan to do as concurrency levels continue to increase, and how will you deal with hundreds or thousands of cores? If your domain doesn't easily benefit from parallel computation, then explaining why is interesting, too. Finally, I've framed this as a multicore question, but feel free to talk about other types of parallel computing. If you're porting part of your app to use MapReduce, or if MPI on large clusters is the paradigm for you, then definitely mention that, too. Update: If you do answer #5, mention whether you think things will change if there get to be more cores (100, 1000, etc) than you can feed with available memory bandwidth (seeing as how bandwidth is getting smaller and smaller per core). Can you still use the remaining cores for your application?

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• How to detect whether a control is standard or active-x control?

  - by Gopalakrishnan Subramani

  In MFC Application, how can we differentiate whether a control is a standard control like CComboBox or it is an custom active-x control?

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• Cleanup for control inside a FlowDocument

  - by Thorarin

  I have a custom control that I use inside a FlowDocument. The control uses a System.Drawing.ImageAnimator to display transparent, animated GIF images. Why is this such a pain in the butt in WPF anyway? :P In my original implementation, this was causing memory leaks when a paragraph containing the control was being deleted from the document, because the ImageAnimator kept a reference to the control for event handling. I've now implemented a WeakEventManager pattern which seems to indeed fix the leak itself, but I would like to stop "OnFrameChanged" events from being fired if a particular animated GIF is not currently in the document, instead of relying on the garbage collector to eventually collect the control objects and my event manager to notice that there no longer are valid listeners to the event. Basically, I would like to take a more active role in this and have the control react to being removed from the FlowDocument. Is there some way to do this? I've been unable to find it. OnVisualParentChanged doesn't get fired, because the direct parent (a Paragraph) is unchanged.

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• C# Multithreaded Domain Design

  - by Thijs Cramer

  Let's say i have a Domain Model that im trying to make compatible with multithreading. The prototype domain is a game domain that consists of Space, SpaceObject, and Location objects. A SpaceObject has the Move method and Asteroid and Ship extend this object with specific properties for the object (Ship has a name and Asteroid has a color) Let's say i want to make the Move method for each object run in a seperate thread. That would be stupid because with 10000 objects, i would have 10000 threads. What would be the best way to seperate the workload between cores/threads? I'm trying to learn the basics of concurrency, and building a small game to prototype a lot of concepts. What i've already done, is build a domain, and a threading model with a timer that launches events based on intervals. If the event occurs i want to update my entire model with the new locations of any SpaceObject. But i don't know how and when to launch new threads with workloads when the event occurs. Some people at work told me that u can't update your core domain multithreaded, because you have to synch everything. But in that case i can't run my game on a dual quadcore server, because it would only use 1 CPU for the hardest tasks. Anyone know what to do here?

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• Thread-safe initialization of function-local static const objects

  - by sbi

  This question made me question a practice I had been following for years. For thread-safe initialization of function-local static const objects I protect the actual construction of the object, but not the initialization of the function-local reference referring to it. Something like this: namspace { const some_type& create_const_thingy() { lock my_lock(some_mutex); static const some_type the_const_thingy; return the_const_thingy; } } void use_const_thingy() { static const some_type& the_const_thingy = create_const_thingy(); // use the_const_thingy } The idea is that locking takes time, and if the reference is overwritten by several threads, it won't matter. I'd be interested if this is safe enough in practice? safe according to The Rules? (I know, the current standard doesn't even know what "concurrency" is, but what about trampling over an already initialized reference? And do other standards, like POSIX, have something to say that's relevant to this?) For the inquiring minds: Many such function-local static const objects I used are maps which are initialized from const arrays upon first use and used for lookup. For example, I have a few XML parsers where tag name strings are mapped to enum values, so I could later switch over the tags enum values.

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• How to allow one thread to mutate an array property while another thread iterates on a copy of the a

  - by Steve918

  I would like to implement an observer pattern in Objective-C where the observer implements an interface similar to SKPaymentTransactionObserver and the observable class just extends my base observable. My observable class looks something like what is below. Notice I'm making copies of the observers before enumeration to avoid throwing an exception . I've tried adding an NSLock around add observers and notify observers, but I run into a deadlock. What would be the proper way to handle concurrency when observers are being added as notifications are being sent? @implementation Observable -(void)notifyObservers:(SEL)selector { @synchronized(self) { NSSet* observer_copy = [observers copy]; for (id observer in observer_copy) { if([observer respondsToSelector: selector]) { [observer performSelector: selector]; } } [observer_copy release]; } } -(void)notifyObservers:(SEL)selector withObject:(id)arg1 withObject:(id)arg2 { @synchronized(self) { NSSet* observer_copy = [observers copy]; for (id observer in observer_copy) { if([observer respondsToSelector: selector]) { [observer performSelector: selector withObject: arg1 withObject: arg2]; } } [observer_copy release]; } } -(void)addObserver:(id)observer { @synchronized(self) { [observers addObject: observer]; } } -(void)removeObserver:(id)observer { @synchronized(self) { [observers removeObject: observer]; } }

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• For each <item> in CheckedListBox. <item> returns as Object and not as Control

  - by Tivie

  Hello there. I have a CheckedListBox previously populated. I want to loop with a "for each / next" through all items in the CheckedListBox and do a lot of "stuff" with each iteration element of the checkedlistbox. example code: For Each item In CheckedListBox1.Items If item.Checked = True Then 'do stuff like item.BackColor = Color.Blue Else 'do other stuff item.BackColor = Color.Brown End If Next the problem is that is an 'Object' type and not a 'Control' type. If I force the iteration var As CheckBox, it throws an InvalidCastException saying that type 'System.String' can't be associated with type 'System.Windows.Forms.CheckBox' I know I can easily work around using for i=0 to CheckedListBox.Items.Count - 1 but I want to use a for each /next loop since I have a lot of code in that loop (and With can't be used) and always poiting directly to the object is something I wish to avoid and I really need the code to be as simple as possible. I actually spent one afternoon looking for this but couldn't find any answer. If someone could be kind enough to enlight me in this, it would be extremely appreciated. Best regards

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• Why wouldn't the default Control Adapter mappings work on Chrome or Safari?

  - by Deane

  I have confirmed that my Control Adapters are not triggering in Chrome and Safari. I've debugged, and the breakpoints inside the adapters just don't get hit in Chrome/Safari, when they work perfectly find in Firefox/IE. So, for Chrome/Safari, IIS is just ignoring the mapping. My AdapterMappings.browser file looks like this: <browsers> <browser refID="Default"> <controlAdapters> [...adapters here....] </controlAdapters> </browser> </browsers> This should provide mappings for all browsers, correct? I used the Charles proxy to check what user agents were being sent. They are: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.1.249.1064 Safari/532.5 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/531.22.7 (KHTML, like Gecko) Version/4.0.5 Safari/531.22.7 Any idea why this would be? Everything I've read tells me that my browser mappings are correct? And, as I said this works for IE/Firefox, so I know my configuration is technically correct.

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• Compact Framework - ListView like control ?

  - by no9

  Hello. I have been playing with Compact Framework lately and i need some advice. I have a collection of items. One of the properties on each item is a string type that holds XML. This XML defines image, font, style etc... Im looking for a control (similar to listView) that would replace listBox control. Im not satisfied with listView control, because it is very limited on items level. The control has to be dynamic enough so that my parser could parse the XML and customise the control. For a start i would like to show an image and perhaps some font styles for each row in the control. Here is a sample what im trying to achieve: Any suggestions?

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• ASP.NET: CSS friendly calendar control

  - by pbz

  I'm using the built-in Calendar control. It works, but in a few places the way the HTML is rendered is broken or not CSS-friendly and unfortunately cannot be changed (it's hard coded). I was hoping they would fix this in .NET 4.0, but as far as I can tell the Calendar control hasn't been changed at all. Also, as far as I know, there's no CSS adapter for the Calendar control. So, I would need a control that would: Allow me to customize the content of each cell (like OnDayRender works) Allow me to assign CSS classes to any HTML it may render Not render anything automatically that cannot be turned off, except layout code No auto-postback or auto-JS code (I can handle these by hand using simple links or custom JS calls) Basically a simple calendar view control that would give me full rendering control. What would you recommend? Thanks!

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• What to use for version control with Visual Studio 2008 for inhouse projects?

  - by Boog

  We want to put a number of our in-house projects under version control. Our projects are C# .NET applications and assemblies. We originally decided to go Microsoft all the way (as is the norm around here), and tried installing Visual Studio Team Foundation Server. To say the least, it was way more trouble of trying to get a successful install than it's worth, and I'm afraid we don't have a entire server to dedicate to TFS itself, as the installer seems to insist. We also considered a generic solution like Subversion or CVS, or possibly some kind of free online hosting that doesn't make our source publicly available under some license like Google Code appears to. Does anyone have any suggestions for us that would best fit our in-house MS environment? We'd also get some benefit out of some kind of project management tools if they were nicely integrated in to the solution, but this would only be a perk. I should also mention that we haven't entirely ruled out TFS, but it's looking like a pain, so anything you guys have to say for or against it would be helpful.

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• How can I increment a counter every N loops in JMeter?

  - by Dave Hunt

  I want to test concurrency, and reliably replicate an issue that JMeter brought to my attention. What I want to do is set a unique identifier (currently the time in milliseconds with a counter appended) and increment the counter between loops but not between threads. The idea being that the number of threads I have set up is the number of identical identifiers before incrementing and using another. If I had 3 threads with a loop count of 2 I want: 1. Unique ID: <current-time-in-millis>000000 2. Unique ID: <current-time-in-millis>000000 3. Unique ID: <current-time-in-millis>000000 4. Unique ID: <current-time-in-millis>000001 5. Unique ID: <current-time-in-millis>000001 6. Unique ID: <current-time-in-millis>000001 I've tried using Throughput Controllers to increment a counter, as well as several other things that seemed they should work but had no luck. This seems like something JMeter should be able to do. Is there any way to get the value of the loop count?

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• ASP.NET MVC : Good Replacement for User Control?

  - by David Lively

  I found user controls to be incredibly useful when working with ASP.NET webforms. By encapsulating the code required for displaying a control with the markup, creation of reusable components was very straightforward and very, very useful. While MVC provides convenient separation of concerns, this seems to break encapsulation (ie, you can add a control without adding or using its supporting code, leading to runtime errors). Having to modify a controller every time I add a control to a view seems to me to integrate concerns, not separate them. I'd rather break the purist MVC ideology than give up the benefits of reusable, packaged controls. I need to be able to include components similar to webforms user controls throughout a site, but not for the entire site, and not at a level that belongs in a master page. These components should have their own code not just markup (to interact with the business layer), and it would be great if the page controller didn't need to know about the control. Since MVC user controls don't have codebehind, I can't see a good way to do this. Update FINALLY, a good (and, in retrospect, obvious) way to accomplish this. using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; namespace K.ObjectModel.Controls { public class TestControl : ViewUserControl { protected override void Render(System.Web.UI.HtmlTextWriter writer) { writer.Write("Hello World"); base.Render(writer); } } } Create a new class which inherits ViewUserControl Override the .Render() method as shown above. Register the control via its associated ASCX as you would in a webForm: <%@ Register TagName="tn" TagPrefix="k" Src="~/Views/Navigation/LeftBar.ascx"%> Use the corresponding tag in whatever view or master page that you need: <k:tn runat="server"/> Make sure your .ascx inherits your new control: <%@ Control Language="C#" Inherits="K.ObjectModel.Controls.TestControl" %> Voila, you're up and running. This is tested with ASP.NET MVC 2, VS 2010 and .NET 4.0. Your custom tag references the ascx partial view, which inherits from the TestControl class. The control then overrides the Render() method, which is called to render the view, giving you complete control over the process from tag to output. Why does everyone try to make this so much harder than it has to be?

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• What is an efficient strategy for multiple threads posting jobs and waiting for response from a single thread?

  - by jakewins

  In java, what is an efficient solution to the following problem: I have multiple threads (10-20 or so) generating jobs ("Job Creators"), and a single thread capable of performing them ("The worker"). Once a job creator has posted a job, it should wait for the job to finish, yielding no result other than "it's done", before it keeps going. For sending the jobs to the worker thread, I think a ring buffer or similar standard fan-in setup would perhaps be a good approach? But for a Job Creator to find out that her job has been done, I'm not so sure.. The job creators could sleep, and the worker interrupt them when done.. Or each job creator could have an atomic boolean that it checks, and that the worker sets. I dunno, neither of those feel very nice. I'd like to do it with as few (none, if possible) locks as absolutely possible. So to be clear: What I'm looking for is speed, not necessarily simplicity. Does anyone have any suggestions? Links to reading about concurrency strategies would also be very welcome!

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• Event handling for a dynamically added user control

  - by francisf

  Hi, I have a user control say SearchVendor.ascx which contains 4 buttons a gridview and another user control. I need to load the control dynamically actually as a modal pop up I get this code VendorProductSearch uc = Page.LoadControl("~/Controls/Proposal/VendorProductSearch.ascx") as VendorProductSearch; uc.ShowVendorProductSearch(true); _tempPlaceHolder.Controls.Add(uc); it works fine the control gets loaded properly but onclick of any button the second time the control disappears ??? I want the dynamically added control to remain until the user clicks on the cancel button Any idea as to how to achive this ? Thanks & Regards, Francis P.

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• Sequential access to asynchronous sockets

  - by Lars A. Brekken

  I have a server that has several clients C1...Cn to each of which there is a TCP connection established. There are less than 10,000 clients. The message protocol is request/response based, where the server sends a request to a client and then the client sends a response. The server has several threads, T1...Tm, and each of these may send requests to any of the clients. I want to make sure that only one of these threads can send a request to a specific client at any one time, while the other threads wanting to send a request to the same client will have to wait. I do not want to block threads from sending requests to different clients at the same time. E.g. If T1 is sending a request to C3, another thread T2 should not be able to send anything to C3 until T1 has received its response. I was thinking of using a simple lock statement on the socket: lock (c3Socket) { // Send request to C3 // Get response from C3 } I am using asynchronous sockets, so I may have to use Monitor instead: Monitor.Enter(c3Socket); // Before calling .BeginReceive() And Monitor.Exit(c3Socket); // In .EndReceive I am worried about stuff going wrong and not letting go of the monitor and therefore blocking all access to a client. I'm thinking that my heartbeat thread could use Monitor.TryEnter() with a timeout and throw out sockets that it cannot get the monitor for. Would it make sense for me to make the Begin and End calls synchronous in order to be able to use the lock() statement? I know that I would be sacrificing concurrency for simplicity in this case, but it may be worth it. Am I overlooking anything here? Any input appreciated.

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• Message sent to deallocated instance which has never been released

  - by Jakub

  Hello, I started dealing with NSOperations and (as usual with concurrency) I'm observing strange behaviour. In my class I've got an instance variable: NSMutableArray *postResultsArray; when one button in the UI is pressed I initialize the array: postResultsArray = [NSMutableArray array]; and setup the operations (together with dependencies). In the operations I create a custom object and try to add to the array: PostResult *result = [[PostResult alloc] initWithServiceName:@"Sth" andResult:someResult]; [self.postResultsArray addObject:result]; and while adding I get: -[CFArray retain]: message sent to deallocated instance 0x3b40c30 which is strange as I don't release the array anywhere in my code (I did, but when the problem started to appear I commented all the release operations to be sure that they are not the case). I also used to have @synchronized section like below: PostResult *result = [[PostResult alloc] initWithServiceName:@"Sth" andResult:someResult]; @synchronized (self.postResultsArray) { [self.postResultsArray addObject:result]; } but the problem was the same (however, the error was for the synchronized operation). Any ideas what I may be doing wrong?

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• WPF: Template Binding in Control template

  - by Sam

  I have the following control template. I wish to set the source property for the image control in the control template using Template Binding. But since this is a control template for button control and the button control doesn't have source property, i can't use TemplateBinding in this case. <ControlTemplate x:Key="BtnTemplate" TargetType="Button"> <Border CornerRadius="5" Margin="15" Cursor="Hand"> <StackPanel> <Image Name="Img" Style="{StaticResource ImageStyle}" Source="temp.jpg" Height="100" Width="100" Margin="5"></Image> <Label Content="{TemplateBinding Content}" Background="Transparent" Margin="2"></Label> </StackPanel> </Border> </ControlTemplate> Since i have to set different images for different instances of button, i can't hardcode the path as well. Please let me know how to tackle this situation.

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• Custom control packaging

  - by CSharpened

  Quick question: You are building a setup for your application. The application contains a custom control developed by you, which will be shared across multiple applications. How should you package the custom control? Package the control in a Merge Module (.msm) and add the .msm file to a Windows Installer project. Package the control into a cabinet project (.cab) and add the .cab file to a Windows Installer project. Create a separate directory for the control and then package it in a Windows Installer project along with the rest of the project files. Package the control as a Web setup project and create a link to that project from the Windows Installer project. Any ideas?

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• Universal control - simple question about dock and anchor

  - by Vytas999

  I use Visual Studio .NET to develop internal applications. I create a Windows control that will display custom status bar information. Different developers will use the control to display the same information in many different applications. The control must always be displayed at the bottom of the parent form in every application. It must always be as wide as the form. When the form is resized, the control should be resized and repositioned accordingly. How should I do that in the best way and why? A)Create a property to allow the developers to set the Dock property of the control. Set the default value of the property to AnchorStyle.Bottom. B) Create a property to allow the developer to set the Anchor property of the control. Set the default value of the property to AnchorStyle.Bottom.

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