One Modal Button: solving one big BG UI problem

BG(1/2) has a lot of different modal abilities which a character can attempt:
- Guard
- Turn Undead
- Stealth
- Detect Traps / Illusions
- Bard Song

These modal abilities share a couple of features:
- You can only do one of them at a time.
- Feedback about the ability is provided in the button itself (highlight around the ability, or greyed out for a Stealth cooldown).

My insight is as follows: since you can only do one of these at a time, you don't need multiple buttons. Let's just have one button for ALL modal abilities. You can switch which modal ability is available just like you switch between quick spells: right click (or long tap) to bring up a list of available modal abilities, pick one, done.

This will be hugely useful to the Cleric/Thief, but it will benefit everyone with more than one modal action, including every plain old Thief.

[spoiler]
It also opens the door to allowing kits / effects which grant extra modal buttons, if the developers wish to grant that ability to modders. Like, a Necromancer who can Turn Undead, or a Paladin of Sune who can sing.
[/spoiler]