Comment 8 for bug 1036884

Re comment 6 - there is no other documentation available, that's what comes up with trunk for Help Keys and Mouse reference.

I think the GUI should, at present, ignore ctrl-click and alt-click, rather than remapping them silently to "click".
At least until such time they are actually assigned intended meanings. Letting undefined key/mouse combinations default to who knows what actions is a bad idea. Defined (and documented) should do what is intended, all others should be ignored. Or to flip it over, if one accidentally uses an undefined key combination and it changes the drawing, there is simply no way to determine from the documentation what it is that you might have done. (Which is how I discovered the filled straight line problem in the first place - making one like that was never intended.)