Fix disabled toolbar button actions

[Duane Clark]

Carlos wrote:
> Hello,
> 
> Testing 12zip.exe, found that you can click in a 
> toolbar button what is disabled, and it shows a window.
> The next patch fixes the problem, please if someone
> is working in the toolbar code, check if it is a correct fix.
> 
> Changelog:
>  * Fix disabled toolbar button actions.

On one of my apps, fpga_editor, this completely breaks the main toolbar. 
The active buttons no longer work at all.

Oddly enough, this app has a popup window with it's own toolbar. The 
buttons on this window have always appeared to be disabled, even though 
only some of them should be. But despite their appearance, the buttons 
work correctly, both before and after this patch.