In the PC, when you drag-select in a single-line textbox, then move the mouse below the textbox, it selects up to the char parallel to the horizontal part of the mouse position. When you press shift-down, it extends the selection by one character. In the Mac (as I recall - no Mac nearby), when you drag-select and move the mouse below the window, it extends the selection up to the end of the line. Same thing with shift-down. In the Moz UI widgets, neither of the above happens. The selection just freezes where the mouse was last seen inside the window.

making wholesale changes to component, QA, and owner. Pass it back if I'm wrong.

I think the way it is now is better for selecting. it will not mess up the scrolling in a text widget that may require it. it provides more leniancy for selection.

In principal, I agree with yossioren's comments. Currently, we're implementing (cross-platform) the behavior that he notes as being the Windows behavior, both on Mac OS and Windows. Mike, I'm going to re-open this as Resolved/Later, in the event that it may be practical in a future version to adopt the platform-specific conventions that users on each platform will prefer. Of course, please re-open if this altered resolution is not to your satisfaction. Thank you!

Adam, as far as I can tell this bug report is about the same thing as bug 19191, "[Mac] Text selection not per HIG (not selecting entire line)", FIXED. Is that correct?

Yes, this appears to be the same bug. It is supposedly already fixed, although in one of the recent builds it broke again. I guess we can take that up there. - Adam

LATER is deprecated per bug 35839.

*** This bug has been marked as a duplicate of 19191 ***