[GUI] File menu "exit" modal does not actually exit the program, while the corner [X] modal does.

[Sleet01]

Environment

Description

The exit prompt modal that appears when user selects File -> Exit does not exit MegaMekLab.
The exit prompt modal that appears when a user clicks on the [X] button in the top-right corner of the frame does exit.

Expectation:

• Both methods instantiate the same modal with the same code and functionality.
• Answering "Yes" or "No" in the Modal either saves, or does not, followed by exiting the program.

Actual:

• They don't function the same.
• Neither option in the first modal exits.

This affects both custom and cache-only units.
This happens whether the user selects "Yes" or "No", although the Save functionality does work in both modals.

Files

megamek.log

CLI debug logging for MML showing File -> Exit modal saving but not exiting, then [X] modal saving and exiting.

20230729_1605_mml_exit_issue.log

[Sleet01]

Cause is: menu entry's frame is the menu bar, while the exit button's frame is the main UI frame. Need to instantiate the Exit menu entry's exit call with the main UI frame somehow.

Actual cause: menu item "Exit" never actually calls System.exit(); it just returns a boolean that is dropped immediately and does nothing.

Proposed fix: wrap the existing lambda in a conditional exit function that will exit if that is appropriate.