Fixed menu bar disappearing when autohide is disabled

[JWangAeronavics]

This fixes the double event handler registration issue described in issue #1682

[edwinhayes]

@JWangAeronavics, is this still broken in master?

[JWangAeronavics]

@edwinhayes the problem still exists in master

[meee1]

there is a other underlying issue here that has been created. if a user wants to enable autohide, with the current structure they cannot, as it is forced by the displayview.

[JWangAeronavics]

@meee1 sorry that's my bad, the above commit fixes that issue.

[meee1]

can you actually tell me how the original issue is created? as I cant replicated the underlying issue.

[JWangAeronavics]

Steps to reproduce:

1. turn on autohide
2. quit mission planner and ensure the menu_autohide config is set in config.xml
3. restart mission planner
4. disable autohide
5. mouse over the menubar then move the cursor off the menubar

this assumes there is no theme that forces autohide present

[meee1]

I still cant replicate this issue. this feature is broken however as the setting is not remembered between sessions. my test was with no displayview defined in settings at all. and as per your instructions.

[JWangAeronavics]

can you repeat this test either with e9107bf5d79eb5fbdc8edff2031bc39f67459fbe cherry picked in or the autohide displayview change #1684 reverted?