Zoom with CTRL+Mousewheel Causes Error

[dloiola]

When trying to zoom in/out with CRTL+Mousewheel Étui closes with an error.

[vtorri]

problem is that zoom out is not limited, hence memory allocation failure. I'm working on it

[vtorri]

more complicated, it's a race condition. I have anyway limited zoom in 2cad24e