Net Tracer "Trace path" not working when zooming

[klayoutmatthias]

To reproduce:

• Prepare a layout and connectivity for net tracer
• Open Tools/Trace net dialog
• Select "Trace Path"
• Select first point
• zoom in with the mouse wheel and select second point

Effect: the second point is not recognized and "Trace Path" is not working. Only when not using the mouse for anything else than selecting the second point, the function works. This is pretty inconvenient.

For the full story see https://www.klayout.de/forum/discussion/2810/trace-path-issue#latest

[klayoutmatthias]

Problem was actually that the start point was not recognized when it left the viewport.

The fix includes some other useful patches:

• The message ("Click on first/second point") is sticky now
• "Esc" leaves trace path mode
• The mouse cursor switches back to normal on the end of the trace path