Middle Mouse Button Handling

[WerySkok]

Hello, I would like to request a separate interface for the handling of the middle mouse button behavior. Specifically, I would like to propose the following options:

1. Paste from Selection Clipboard: This option would mimic the traditional behavior from X, where clicking the MMB in an application would paste the content from the selection clipboard into that application. Thanks to Wayland transition, this option is now isn't the only possible one.

2. Autoscrolling: This option would enable autoscrolling, like in Windows. Clicking the MMB in a scrollable area would activate autoscrolling, allowing users to smoothly scroll through content without manually dragging the scrollbar.

3. None: This option would disable any specific middle mouse button behavior in xdg-desktop-portals, allowing applications to define their own custom functionality if desired.

[WerySkok]

I also think that enabling both Paste&Scroll should not be possible because that may lead to many undesired Paste actions in case if user just wanted to scroll through the content

[Mikenux]

What do you mean? That pasting and autoscrolling shouldn't happen at the same time when the MMB is pressed, or that pasting should be disabled when scrolling? I'm asking this because I don't know if it's possible to assign two shortcuts to the MMB.

[Play-InTheWay]

It probably means that pasting and autoscrolling shouldn't happen at the same time when the MMB is pressed. Something like that unfortunately can happen on Webcord and it's pretty undesirable.

[Mikenux]

Paste should be certainly disabled in both cases.

[Mikenux]

Is Autoscrolling implemented system-wide in a desktop environment?

[Play-InTheWay]

I don't think so, but it could be implemented from the toolkit or application side (as it kind of currently is).

I'm thinking that it may fit well in the Settings portal, though it wouldn't be an appearance setting.

[Mikenux]

I don't think so, but it could be implemented from the toolkit or application side (as it kind of currently is).

Thanks. That's important as in a UI allowing the user to select which action to trigger from the MMB, we can't attest that it will autoscroll if it isn't sure it will.

I'm thinking that it may fit well in the Settings portal, though it wouldn't be an appearance setting.

Don't know which portal it belongs to. In the settings portal and for the settings exposed, the user isn't asked for something. Here, I guess the app needs to declare if it supports MMB shortcuts and which ones. I also have #1395, and this may be part of it (while not fully related) if it is approved.

[WerySkok]

KDE added autoscrolling in Plasma 6.2, though it works differently than on Windows: instead of acceleration based on the distance of the mouse from the starting point, Plasma just tied the scroll to the mouse position.

[Mikenux]

Ok, this is a libinput thing. The portal backend will indicate whether the DE supports the feature. Now I guess it's up to the portal maintainers to decide whether this would be part of a clipboard portal (thus conditioned on its development) or would be something independent.

[whot]

Ok, this is a libinput thing.

libinput has on-button scrolling which is a bit different to the autscrolling feature.

on-button scrolling unconditionally changes mouse motion events into scroll events while a given button is held down. autoscrolling usually works only on supported surfaces and has some related UI to indicate the actual scroll movements and the scroll itself isn't necessarily based on mouse movement but regular deltas generated based on the distance to the original point (like @WerySkok said).

The end result is roughly the same but it works on a higher level than the libinput feature.