I wish that (at least optionally) the Quick Menu could be displayed and stay displayed by clicking and letting up on the SPACEBAR. In this mode, the palette could be cleared when the user moves to cursor out of the palette’s rectangle, or perhaps something more explicit like clicking outside the rect. (I guess you could call this making it “sticky”). This would make it easier to either do multiple things from the palette before dismissing, or do things requiring other key/mouse combinations to be pressed such as Alt-Click on e.g. the Alpha swatch to cause the Alpha menu to be displayed in one of the side trays.
UPDATE: I discovered that just RCLICK’ing on the canvas does something of what I was suggesting for SPACEBAR. With the RCLICK method, the palette remains displayed until you select an item or mouse off the palette.