Add mouse/keyboard resizing of views

[tig]

Right now, dragging is handled w/in TopLevel. This needs to change to be handled within Border (or in Application, but via an interface with Border).

• Define ViewArrangement.Movable - if set and view has a top Border, it can be dragged with mouse. Always with keyboard (although no visual indicator if no border).
• Define ViewArrangement.Sizable - if set and a view has left/right/bottom Border it can be resized with mouse. Always with keyboard (although no visual indicator if no border).
• Determine keyboard drag/size UI
• Remove temporary hack in Application.cs:

Related:

• #Discuss - There should only be one (Application.Top) #2502.

My proposal:

Tiled Mode:

Mouse:

• Dragging Border top or bottom resizes the view vertically
• Dragging Border left or right resizes the view horizontally

Keyboard:

• Hit Ctrl+F5 to enable Arrange Mode ¹
• A line will get a ◊ indicating it's active for resizing. Left/Right/Up/Down will size.
• Tab to move to next line
• Shift-Tab to move back
• Ctrl+F5 or Esc to exit Arrange Mode

Overlapped mode:

Mouse:

• Dragging Border top moves the view
• Dragging Border bottom resizes the view vertically
• Dragging Border left or right resizes the view horizontally

Keyboard:

• Hit Ctrl+F5 to enable Arrange Mode ¹
• A ◊ appears in top left corner of Border indicating Arrange Mode
• If ViewArrangement.Movable is set Left/Right/Up/Down will move the view
• Tab and Shift+Tab will cycle through any sides that can be sized and "Move"
  • UNLESS: ViewArrangement.Resizable (all side-flags) is set. Then ◊ appears in bottom right corner of Border.
• A side selected for sizing will get ◊ centered indicating it's active for resizing.
• Left/Right/Up/Down will size as appropriate
• Ctrl+F5 to exit Arrange Mode

Footnotes

1. On Windows Alt-Space, M enables move-with-keyboard. On Mac Ctrl-F5 "Move focus to the window toolbar". No standard on Linux. Ctrl-F5 isn't used by Windows Terminal. Happy for a better suggestion. ↩ ↩²

[tig]

This needs to fix #2536 too

[tig]

Based on @Nutzzz's excellent SpinnerView enhancments, I propose we use SpinnerView to show which border has focus for sizing instead of the diamond that @tznind originally used for TileView.

E.g. This one for horizontal:

and this one for vertical:

This will require LineCanvas to support hosting a SpinnerView as a point (where .Length == 0) I think.

[Nutzzz]

Y'know, I like the idea in general, but I'm personally not thrilled about those spinners in particular. I feel like one of these might be better (if not perfect).

[What do you think, 2-frame or 3-frame?]

2 frames, horizontal and vertical:

3 frames, horizontal and vertical:

[tig]

@BDisp this is another Issue related to

• Master Issue: Finish Adornments  #2994