Hi,
It seems that there is a problem with fullscreen mode on Mac OS X : when you have a window with a toolbar, if you switch to fullscreen mode, all controls at the top are disabled (no click event). It appears that’s is the area under the toolbar when the menubar is not hidden.
I’m not sure there is a feedback for this problem, I’m going to add one.
In my case, this area contains the search one and some contextual buttons. I can’t use fullscreen mode with my app 
I’ve made a screenshot to explain the problem :
In that case, the OK button can’t be clicked.
Is it the same on 10.9.4 or just 10.10?
(Just curious)
Not try yet on 10.9, just tested with 10.10.
[quote=123181:@Pascal PLUCHON]Hi,
It seems that there is a problem with fullscreen mode on Mac OS X : when you have a window with a toolbar, if you switch to fullscreen mode, all controls at the top are disabled (no click event). It appears that’s is the area under the toolbar when the menubar is not hidden.
I’m not sure there is a feedback for this problem, I’m going to add one.
In my case, this area contains the search one and some contextual buttons. I can’t use fullscreen mode with my app
I’ve made a screenshot to explain the problem :
In that case, the OK button can’t be clicked.[/quote]
You could probably apply the declare Jim McKay uses in this project
http://www.pidog.com/share/blackwindowFinalFinal.xojo_binary_project
from the discussion https://forum.xojo.com/10914-black-windows
to place a canvas on the window bar. I have used it since to place buttons on a toolbar. With some luck, it can restore your controls functionality.
BTW, Xojo IDE has this problem too… If fullscreen mode, the icons above the toolbar doesn’t respond too.
Ok, it’s a 10.10 bug only… Seems to work fine in 10.9
Report it in Feedback if it isn’t reported already 
Ok, I’ve reported a feedback : <https://xojo.com/issue/35014>
I checked, and the declare I referred to above unfortunately cannot help.
Until the bug is fixed, a workaround is possible through System.MouseX, System.MouseY and System.MouseDown. It works fine in a timer that monitors these informations.