Pile up events in nested event loops.
Remove strokes to provide a more accurate timing of graphs on the screen.
Draw a fine line between any two levels.
Merge branch 'pile-up-nested-event-loops' into thinker
The same color for all threads with the same process ID.
Merge pull request #15 from ThinkerYzu/thread-color

Give the color for all threads with the same process ID.