How to always show menubar with fullscreen apps?
You can adjust this on a per-app basis by editing the plist. My memory is rusty but here are instructions, if I remember correctly.


Show package contents for the app you want
Edit the file Contents/info.plist
Search for "LSUIPresentationMode" (you may want to use a plist editor). It will look like this if you use a regular text editor:

&lt;key&gt;LSUIPresentationMode&lt;/key&gt;
&lt;integer&gt;4&lt;/integer&gt;


If the property does not exist, then you can create it - it must be inserted in the correct alphabetical order.
Change the value of the integer accordingly:


LSUI PresentationMode 0 - Does not hide Dock or Menu Bar.
LSUIPresentationMode 1 - Hides Dock. Dock will appear if mouse moved to where it is located. Menu Bar will remain.
LSUIPresentationMode 2 - Removes Dock. Menu Bar will remain.
LSUIPresentationMode 3 - Removes Menu Bar and Dock.
LSUIPresentationMode 4 - Hides Menu Bar and Dock. Menu Bar or Dock will appear if mouse moved to where Menu Bar or Dock is located.



For more information on LSUIPresentationMode usage, see the developer documentation: 

http://developer.apple.com/library/mac/#documentation/General/Reference/InfoPlistKeyReference/Articles/LaunchServicesKeys.html#//apple_ref/doc/uid/TP40009250-113616-TPXREF134