More updates to comments.
Giant commit: implemented event handling for click-and-cross correctly. Fixed the F4 hotkey.

It now works by supplying a CONST.guessedTarget event in two places. First, when a normal click is done on the iFrame body (i.e. in the adaptive case), then it does this. Next, when click and cross is done, it triggers events on the sibling, in which the handler is removed only if the correct target is crossed (by checking a new class that was created in iFrame.css for the current target).
Added logging for both initiated and cancelled click and cross.
Added logging to a file for the end of a trial -- in addition to MySQL