Mouse panning (middle-button scrolling)

[mcpiroman]

Summary of the new feature/enhancement

Introduce scrolling with middle mouse button, common to browsers/text editors and also available in conhost.

Currently middle mouse button is not used (right?) but there are requests to use it to paste text, so there needs to be a settings for that.

Proposed technical implementation details (optional)

PR #1523 introduces mechanism to implement scrolling, cursor image has to be replaced with appropriate images.

[miniksa]

Does this conflict with the proposal from #1612?

That's my major concern.

Also, I don't mind implementing panning on middle mouse if that's what we decide to do (instead of copy-paste) to make it more like conhost.

My only concern is that conhost accomplished the middle click panning through a gross, old, private API call. I don't want to accomplish it the same way. If we can do it another way, I'm good with that.

[mcpiroman]

My only concern is that conhost accomplished the middle click panning through a gross, old, private API call. I don't want to accomplish it the same way. If we can do it another way, I'm good with that.

Good to hear that, couse the function that conhost uses indeed seemed scary.

[DHowett-MSFT]

@carlos-zamora agrees this should be the middle button binding. We have consensus!

[mcpiroman]

Actually this don't quite have to be the middle mouse button, mice have more of them (tho my's 'nly 3). It could be even keybinding. But that seems related to #1553.