Suggestion 1: SKETCHER
We all LOVE the delete Segment tool that has been around a long time. Can you have another tool that does the inverse???
When I drag a line across 2 lines it could automatically extend them until they meet at a corner. If the lines are parrallel I guess it would automatically "forget the first line that you crossed, and wait for a 3rd line that can form a corner with the second. I hope I am not making this more confusing than it is..
Could call it "Corner Segment or Extend Segment..... with a green squiggly line on the icon and 2 perpindicular lines that don't current meet at a corner" This could be a flyout for the "CORNER" tool as another option
Suggestion 2: SKETCHER
When I am in sketcher and have sketched a box, I want to be able to pick on a corner of the box to place a radius that is trimmed and automatically tangent. Similar to picking an edge in modeling mode to place a radius. This may be tricky because the point would have to know that it is a corrner and not just the end of a line segment. But I suppose the command would just not work if you picked a point at the end of a line. It would be a great feature though and save time.
Steve C