Sticky Keys backend

Design task: T42339
Differential Revision: D840
Initial implementation proposal: T41867

Short description:
With this we can distinguish between holding and tabbing a key. Useful
is this if we want to assign to operators to a single shortcut. If two
operators are assigned to one shortcut, we call this a sticky key.

More info is accessible through the design task and the diff.

A few people that were involved with this:
* Sean Olson for stressing me with this burden ;) - It is his enthusiasm
that pushed me forward to get this done
* Campbell and Antony for the code and design review
* Ton for the design review
* All the other people that gave feedback on the patch and helped to
make this possible

A big "Thank You" for you all!

1 files changed, 9 insertions, 2 deletions

diff --git a/source/blender/editors/space_text/text_ops.c b/source/blender/editors/space_text/text_ops.c
index ad8050a50e8..6fb5706bfdf 100644
--- a/source/blender/editors/space_text/text_ops.c
+++ b/source/blender/editors/space_text/text_ops.c
@@ -2163,6 +2163,11 @@ static int text_scroll_modal(bContext *C, wmOperator *op, const wmEvent *event)
 		case LEFTMOUSE:
 		case RIGHTMOUSE:
 		case MIDDLEMOUSE:
+			/* don't exit on dummy events */
+			if (event->val == KM_NOTHING) {
+				return OPERATOR_RUNNING_MODAL;
+			}
+
 			if (ELEM(tsc->zone, SCROLLHANDLE_MIN_OUTSIDE, SCROLLHANDLE_MAX_OUTSIDE)) {
 				txt_screen_skip(st, ar, st->viewlines * (tsc->zone == SCROLLHANDLE_MIN_OUTSIDE ? 1 : -1));
 
@@ -2667,8 +2672,10 @@ static int text_set_selection_modal(bContext *C, wmOperator *op, const wmEvent *
 		case LEFTMOUSE:
 		case MIDDLEMOUSE:
 		case RIGHTMOUSE:
-			text_cursor_set_exit(C, op);
-			return OPERATOR_FINISHED;
+			if (event->val != KM_NOTHING) {
+				text_cursor_set_exit(C, op);
+				return OPERATOR_FINISHED;
+			}
 		case TIMER:
 		case MOUSEMOVE:
 			text_cursor_set_apply(C, op, event);