Mouse wheel for zooming : Effect of Alt-Wheel

Moderator: jsachs

Post Reply
pierrelabreche
Posts: 64
Joined: January 29th, 2019, 11:47 pm

Mouse wheel for zooming : Effect of Alt-Wheel

Post by pierrelabreche »

Hi Jonathan,

Mouse scrolling is sometimes ignored under some conditions not completely deterministic.

Some scenarios :
File>Open

Scroll the mouse wheel up and down : zooming is effective
Scroll the mouse wheel up and down while Alt is pressed : zooming is effective
Scroll the mouse wheel up and down : zooming is ineffective

Scroll the mouse wheel up : zooming-in is effective
Scroll the mouse wheel up and down while Alt is pressed : zooming is effective

Scroll the mouse wheel up while Alt is pressed : zooming-in is effective
Scroll the wheel down (without Alt) : zooming-out is ineffective, then zooming is ineffective

...
Scroll the mouse wheel down while Alt is pressed : zooming-out is effective
Scroll the wheel down (without Alt) : zooming-out is ineffective

It is easy to get out of the faulty state by pressing and releasing Alt while scrolling the wheel.

As you noted in another thread, clicking on the transformation window on the left side of the screen does clear the problem.
In the case of "file open", the thumbnail must be clicked once to open the File Open dialog window (not really a transformation window).
Clicking in the dialog window clears the problem.

jsachs
Posts: 3303
Joined: January 22nd, 2009, 11:03 pm

Re: Mouse wheel for zooming : Effect of Alt-Wheel

Post by jsachs »

There appears to be some strange behavior in Windows regarding the Alt key. Simply pressing and releasing Alt seems to deactivate the main window, every other time. This is reflected in the cursor changing from a hand to an arrow. Clicking on the main window makes it work again. I haven't been able to find any documentation of this so for now there is no way I can fix it.
Jonathan Sachs
Digital Light & Color

jsachs
Posts: 3303
Joined: January 22nd, 2009, 11:03 pm

Re: Mouse wheel for zooming : Effect of Alt-Wheel

Post by jsachs »

I believe this is caused by Windows using the Alt key followed by a letter as a keyboard shortcut for menu selection. Pressing it a second time cancels the menu selection mode. It does this even if there is no menu as is the case with PWP which does its own menu processing, bypassing the normal main menu so it can implement custom themes.

The good news is that, having identified the source of the problem, I found a solution online, so it is fixed for the next release.
Jonathan Sachs
Digital Light & Color

Post Reply