Hi Sudarsan,
I am using KDE 4 on Fedora 10. I recently updated it to version 4.1.4.
After this update, whenever i open a KDE application it opens in fullscreen.
I somehow have to reach the panel and disable the fullscreen option.
I googled about it. Some people said that disabling compiz-kde might do the trick but it didn't work for me.
I'm guessing you're using compiz. This actually is a problem with compiz+qt4 combination. Here's how you can resolve this
open compizconfig manager.
scroll down to utilities section and look for 'workarounds'.
uncheck the very first option 'Legacy window fullscreen support'.
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Gunjan Patidar