Editing function from MASTERSCOPE show paths graph locks MOUSE process

[MattHeffron]

Describe the bug
If you use the left mouse button on a node in a MASTERSCOPE show paths graph, the popup menu offers "Edit". Selecting that locks up the mouse process. Using the middle mouse button to directly edit the function doesn't have this problem.

To Reproduce
Steps to reproduce the behavior:

1. Files loaded 'MANAGER, MASTERSCOPE, GRAPHER, and BROWSER'
2. In INTERLISP Exec, type: ED(PRETTYCOM) answer yes to loading PRETTY PROP
3. Exit SEDIT of PRETTYCOM
4. Left mouse click on PRETTY in MANAGER main menu. Select "MasterScope" (don't use SUBMENU)
5. In INTERLISP Exec, type: . SHOW PATHS FROM PRETTYCOM TO EDITLOADFNS?
6. Middle mouse click on a PRETTYCOM node in the graph.
7. Note that it opened SEDIT without locking up access to the mouse.
8. Left mouse click on a PRETTYCOM node in the graph. Select "Edit" from the popup menu.
9. Notice that the mouse cursor still tracks, but you cannot click on anything.
10. Type ctrl-B to enter a BREAK. This spawn's a new mouse process, so clicking works fine now.
11. Type OK in the BREAK. Everything proceeds well.

Expected behavior
Menu selection doesn't lockup the mouse process.

Screenshots
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Context (please complete the following information):

• OS: [e.g. Mac/Linux/Cygwin]
• OS Version: [e.g. High Siera/Ubuntu 18/Raspbian]
• Host arch: [e.g. x86_64, arm7l, arm64, sparc]
• Maiko version: [e.g. commit ID from git log | head]
• IL:MAKESYSDATE: [ date ]

Additional context
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