Hi, you're probably already covering this at the moment behind the scenes. But below are what I'd like to see added to the API.

Code:
Inspect.Mouse.X() -- returns X position of the mouse pointer on the screen
Inspect.Mouse.Y() -- returns Y position of the mouse pointer on the screen
Code:
Event.Mouse.Move() returns new x,y co-ordinates. Possibly not needed with the below in mind.
Code:
-- New Frame Members
Frame:SetAcceptInput() <-- true/false : Allows/Disallows Frame based mouse clicks + modifiers.
Frame:SetActive() <-- true/false : Allows/Disallows Frame base mouse tracking events. See below.

-- New Frame Events
Frame:MouseEnter <-- triggered only when SetActive(true) when the mouse pointer enters the frames area.
Frame:MouseLeave <-- triggered only when SetActive(true) when the mouse pointer leaves the frames area.
As mentioned in SetAcceptInput() I would like the LeftUp/Down, RightUp/Down etc events (when added) to also supply any modifier pressed at the time.

Just something I'm looking forward to, and hopefully you're already working on such things.