Currently most tools are not sticky, i.e. once they are used, the app automatically changes back to the Select tool. The (only?) exception seems to be the Pen tool, which is "sticky", i.e. after tracing a stroke, the tool remains active so I can make further strokes.

I think it would be nice if all tools behaved the same way in terms of stickiness, and for there to be a way to toggle the stickiness when selecting a tool. For example, if all tools are made non-sticky, then e.g. Ctrl+click or double-clicking could make them sticky.

This is how the format painter tool works in Google Docs, for example — a single click selects it in a non-sticky mode, and double-clicking it selects the tool in sticky mode.