Most of my colleagues see our application with the right style :
but for a couple of them tabs look in a different way :
I can't explain why. Any idea?
Any help would be much appreciated.
Is your Isl file turning off themes? When you create a new style library, the first thing it asks you is if you want to turn off themes. The first screen shot you show here looks like it has themes turned off, but the second one appears to have themes on - at least it looks that way based on the button appearance - I could be wrong.
I selected AllComponents in the Roles Tree View and set UseOSThemes as False.
Now it looks ok with XP, Vista and Win7.
Thanks.