So I've now got it so spells/abilities show up on the stack!
Ignoring the fact that I have no business casting
Bogardan Hellkite with 2 lands on the field (thank you Dev Mode

), this is the basic idea. I made it so in addition to the spell/ability text displaying on the stack using the calculated background color, the source card is also displayed. The stack will auto-open when the spell/ability goes on the stack and auto-close when it the stack becomes empty, though you can manually show/hide the stack by clicking the tab.
Next up I'll make it so tapping on the stack opens up the card zoom view where you can scroll though the stack with more detail visible for the source card and ability, as well as activate yields and such.
One question I have it how I should handle multiple things on the stack. Should they overlap at all, and should the top item on the stack appear at the top of the screen below the tab, or at the bottom of stack pane with others partially hidden above it (similar to in MTGO)?
Otherwise, how does this all look and sound?
Thanks.
-Dan