Please, I have been dealing with the alt-tab problem for a long time. I have alreade check keyboard shortcuts in the configuration panel but it still doesn't work. (I already had this problem in ubuntu 12.04, but since I installed 14.04 another problem came arround. I can't add work spaces. I tryed changing the amount of work areas by right clicking in the desktop's miniature but it does't chenge. Anyone can help me find this parameters in a file wich I may be able to edit using "sudo nano" or something similar? Thaks!

PS: I also have problems with the backlight but that may be another issue since I had to install samsung-backlight in 12.04 but it isn't availabe for 14.04. I just mention it in case someone knows somthing about it.