bug#34014: 25.2; binding down mouse event with modifier to mouse-drag-region does not work

[Eli Zaretskii]

> From: Adolf Mathias <adolf.mathias@gmail.com>
> Date: Tue, 8 Jan 2019 10:51:19 +0100
> 
> >From 'emacs -Q' under X11, Ubuntu Bionic Beaver, enter:
> M-: (define-key global-map '[S-down-mouse-1] 'mouse-drag-region)
> 
> Now attempting to drag a region with held down shift key gives the
> error message:
> 
> <S-drag-mouse-1> is undefined
> 
> Redefining the mouse key without shift modifier, and then dragging,
> works as intended:
> M-: (define-key global-map '[down-mouse-1] 'mouse-drag-region)
> 
> This used to work in Emacs 24 and before.

Sorry for such a long delay in responding to your report.

Can you tell why you want to bind S-down-mouse-1 and not
S-drag-mouse-1 to a drag command?