Hello!
When i add a xp manifest resource my dialog (DialogBoxParam) does not appear anymore.
How to solve this?

Nevermind! I found the answer myself.

For those with the same problem; You need to call InitCommonControls() or the dialog will not show if you add a manifest file for having the XP look.

I don't think you actually have to call it, simply referencing it in FASM will cause it to be imported by the macros. (for example) anywhere should be sufficient (at least, it works for me.)

Yes, I also do the same but I'm not sure if it is a documented fact or implementation "abuse". The typical explanation is that InitCommonControls is only one instruction (RET), but I don't know if the documentation makes clear that it will be always a RET on all future Windows versions.