Tool panels
Snapping, brushes, trace

They open from a tool or from a menu, not from the selection.

A tool panel: the list of brushes, opened by hovering over the brush button
9.2.1

Snap panel

Hovering over the snapping button in the toolbar.
9.2.2

Brushes panel

Hovering over the Brush button.
9.2.3

Trace image panel

Right-click menu › Tools › Trace image….