Hello, I'm working on PowerPoint Add-In and I was faced with trouble I couldn't solve myself. The point is I need to change the slide Layout programmaticaly with C# (the Add-In Express 2009 for Office and .NET is used). If the new layout is a predefined one everything is fine but I need to set a custom layout as a new one (without slide recreating). Unfortunately, I didn't find any information on how to do it, PowerPoint object model reference documentation didn't answer me as well. There is just the ability to create a new slide that uses custom layout. I've done an experiment seria and have ensured that the Slide object stayed being the same while I have been changing layout both predefined and custom ones. I don't want to create a new slide when I need just switch the layout. Is it possible at all? Please help me to find a way of doing it. Thanks in advance.