New pref 'browser.bookmarks.openInTabClosesMenu = true' - unexpected behaviour using right-click context menu

[Blacklab]

Pale Moon 32.5.0 added a new preference 'browser.bookmarks.openInTabClosesMenu' (default true) as per Release Notes extract:

By user request, added a preference browser.bookmarks.openInTabClosesMenu (default true) to allow users to configure if they want to keep the bookmarks menu open if they open bookmarks from it in a new tab (by middle-clicking or Ctrl-clicking). The default behavior is to close the bookmarks menu like any other menu when an option in it is clicked.

Situation
The new preference works at expected and as stated when using "middle-clicking or Ctrl-clicking" to open a bookmark in a new tab.
The new preference does not work as expected when using the right-click context menu option 'Open in a New Tab' to open a bookmark.

When opening a bookmark using the 'Open in a New Tab' right-click context menu option the Bookmarks Menu does not auto-close as expected with preference 'browser.bookmarks.openInTabClosesMenu' set to 'true' (default). Instead, when using the right-click 'Open in a New Tab' the Bookmarks Menu remains open regardless of the new preference setting.

Tests
With new preference 'browser.bookmarks.openInTabClosesMenu' set to 'true' (default) in Pale Moon 32.5.0:

1. Test on a new profile of Pale Moon 32.5.0 on Win10:
Open a bookmark from Bookmarks Menu by selecting 'Open in a New Tab' from the right-click context menu:

• EXPECTED RESULT - Selected bookmark opens in a new tab and the Bookmarks Menu closes automatically.

• ACTUAL RESULT - Selected bookmark opens in a new tab and the Bookmarks Menu stays open.

2. Test on a new profile of Pale Moon 32.4.1 on Win10:
Open a bookmark from Bookmarks Menu by selecting 'Open in a New Tab' from the right-click context menu:

• EXPECTED RESULT - Selected bookmark opens in a new tab and the Bookmarks Menu closes automatically.

• ACTUAL RESULT - As expected.

[Moonchild]

Yeah looks like I'll have to back that out for now. I spent quite some time looking into this but I don't see an easy solution because the whole bookmarks menu scripting is incredibly complex due to it being dynamically built, having a million and one different actions to activate bookmark menu items, and it not being simple to determine when a left-click on that menu item (obviously unmodified) should be treated specially. Menus are designed from the ground up to close when activated, and my solution was too shortsighted. This isn't the only behaviour I broke, by the way, so it can't stay in its current form.