[Canvas Input settings] Configure selection settings & Photoshop compatible inconsistencies

Problem
Using the Photoshp compatible Canvas input settings, there are some inconsistencies which take away functionality when using selection tools. In particular, the setting that the line tool is activated while holding shift, which overrides the option to add to selections. Furthermore, there is no way to specify that dragging a selection window while holding Alt would remove from selections.

Proposed solution
A possible solution would be to change the move selection modifier over to the spacebar (which corresponds to the way Photoshop, Blender and Affinity handle this), see below:

This would free up the Alt key to either duplicate the selection window over to other areas of the canvas or to remove from the selection.
In general, I think it would be great to have access to the configuration of modifiers for selection tools, so that users can customise shift to add to selections even within the Photoshop compatible mode. That way, the functionality is not lost, instead, when configured for selections, it would override erratic use of the line tool when selecting.

E: Bug report for the duplicate Canvas input settings can be found here: 437241 – If Canvas Input Settings are 'Paint Tool Sai Compatible', there is loss of functionality