Removed TODO about application-modal dialog boxes in GTK+; they were already application modal! The real issue is window transience... and that's where platforms differ greatly.
Rewrote a TODO on build tags for the Unix build.
And removed that TODO from the previous commit after verifying that such a proposal is too risky.
Decided not to rename MouseEvent.Pos.
Made multiple modifier keys undefined; removed the TODO there. If I need to change the behavior I can do it later.
Added the previous commit to the future plans instead.
Removed the TODO on memstride: we were already using it?????? It is working correctly... No idea why that TODO was there; I know I added it when I was too tired to think though.