key press in a canvas

[Roger Oberholtzer]

I would like to sense when a key is pressed in a canvas. The key is a modifier when the mouse is moved over the canvas. The reason I want to know when the key is pressed or released is that I want to know then the modified mouse activity is ended. This is most easily detected when the modifier key is released. If I just bind on, say, <Alt-Motion>, then I do not know when the Alt key has been released and the activity thus has ended. I think I must be missing something very simple and obvious.

--
Roger Oberholtzer

[Arjen Markus]

Doesn't that generate a ButtonRelease event? I have not tried it, but I can imagine that a change in the state of the modifiers causes a new event.

Regards,

Arjen

[Brad Lanam]

From a quick test, it appears that you will need to watch for the
keypress and keyrelease of your modifier key and only process the
alt-motion when the modifier key is in the pressed state.

Notes:

- alt-mouse movement on linux moves the window around and is not capturable.
- The modifier keys will present themselves as left and right: Alt_L and Alt_R,
and the keypress/keyrelease handlers will have to check for that.

[Rich]

Brad Lanam <brad....@gmail.com> wrote:
> - alt-mouse movement on linux moves the window around and is not capturable.

alt-mouse movement on /some/ linux distros moves the window around.

But not on all linux systems (i.e., at least on mine running Fvwm2,
alt+mouse does absolutely nothing).

[Brad Lanam]

On Monday, June 11, 2018 at 10:43:48 AM UTC-7, Rich wrote:

> Brad Lanam <> wrote:
> > - alt-mouse movement on linux moves the window around and is not capturable.
>
> alt-mouse movement on /some/ linux distros moves the window around.
>
> But not on all linux systems (i.e., at least on mine running Fvwm2,
> alt+mouse does absolutely nothing).

And to be precise, I should have said /most/ linux window managers,
since that's a function of the window manager, not linux.

How does fvwm2 allow you to move a window? Only title bar click-and-drag?

[Rich]

The short answer is: however you configure it to do so.

The defaults allow window move on the title bars, and (maybe, I forget
now) on edges, with resize on any of the four corners.

My setup's configured such that I can move a window with any edge or
with the title bar, and can resize using any edge.

If I wanted to do alt+mouse move to move a window, there is likely a
way to configure it do let me do so (but I've never investigated down
this path).

[Luis Alejandro Muzzachiodi]

What about to check just <Motion> ?.