Source Tree spinning rainbow of death when using external diff on mac OS X

[wcontello]

When I using an external diff tool (File Merge) on mac OS X (10.13), then close the diff file and return to Source Tree, I get the spinning rainbow of death until I close the application "FileMerge"

can anyone else confirm this?

In SourceTree prefs, I have FileMerge selected as the external diff tool

Procedure:

1) Launch Source Tree

2) open you favorite repo

3) highlight a modified file

4) right click selected file and choose "External Diff" from the contextual menu

5) Close the external diff file (but do not quit File Merge)

6) try to make Source Tree active... I get the spinning rainbow of death