In the current trunk, if you have histogram set to shoot, and half shoot in alt mode (play or rec) the histogram appears, and stays after you let up alt. After you release alt, it stops updating, but doesn't go away until you do something that causes a screen update (switch mode, go to menu etc).
This also happens in play mode without alt, if zebra is not enabled.
Any hints on how much of this is intended would be appreciated
Or just say how yo think it should work.
Note: all of the above based on testing a540.