Setting the cursor icon

[robbert-vdh]

Currently there's no way to change the mouse cursor icon from within a WindowHandler. Cursor icons are useful to indicate that UI elements are clickable or that you can enter text to them, but without the ability to set them plugins using baseview also tend to look very buggy in hosts like REAPER where the cursor icon may be stuck on some random non-pointer cursor when interacting with the GUI.

Baseview would not even need to allow you let you use any random cursor icon for this to be useful, just some common cursor types like a pointer, a grab handle, a caret, a crosshair, and a disabled icon would likely be sufficient.