Many enums in Blender are able to have multiple items selected, but this feature isn't exposed very well.
It's not clear which enums support this, so you have to try by pressing shift when clicking on them.
And a lot of the time it's more valuable to have multiple items selected, but it's harder because of the modifier key.
A more straightforward solution is to use the multi-select behavior by default, only turning off all other items off when a modifier key is pressed.
This patch proposes this changed behavior with ctrl as the modifier key.
|Before with No Modifier Keys||Before with Shift|
|After With Ctrl||After with No Modifier Keys|