Bug 1046149

This problem occurs with RHEL7 HTB as well. In fact it may be even worse:

[ben@localhost ~]$ sudo xrandr -q
Screen 0: minimum 320 x 200, current 1680 x 1950, maximum 8192 x 8192
LVDS1 connected 1440x900+150+1050 (normal left inverted right x axis y axis) 287mm x 180mm
   1440x900       60.0*+   50.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 connected primary 1680x1050+0+0 (normal left inverted right x axis y axis) 495mm x 291mm
   1680x1050      60.0*+
   1600x1200      60.0  
   1400x1050      60.0  
   1280x1024      75.0     60.0  
   1440x900       59.9  
   1280x960       60.0  
   1152x864       75.0  
   1024x768       75.1     70.1     60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   640x480        75.0     72.8     66.7     60.0  
   720x400        70.1  
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)

In my case, if in the display settings I put the menu bar on the external monitor then I have trouble moving windows from the top monitor to the bottom monitor. The problem is the bottom panel gets in the way and blocks movement across the interface between the monitors. I have yet to figure out how to move this new panel to either the bottom of the lower display or the side of the top display where it will be out of the way.

If I put the title bar on the internal laptop display which is the lower display then, I have problems moving windows on the top display in the areas above the menubar. There appears to be something blocking placing windows above the menubar. You can however stretch windows into that area.

The second problem is closely related to RH BZ#923211 However, the first part, the way that the lower panel as part of our theme makes this particularly unworkable.

Also it appears like RH BZ#711479 is another user complaining of the same problem but with fedora. So this seems to be a common setup and a common problem.

Yeah the gnome-panel like gnome-shell mode in the default legacy gnome2 UI mode.

Moving out of the legacy session mode makes it much more workable but since the legacy session is the default when you install RHEL7, we should probably deal with this.

okay, it's a little difficult to be sure, since the comment is talking about gnome-panel and gnome-panel source code, but I believe the bug you're referring to is this one:

https://bugzilla.gnome.org/show_bug.cgi?id=663690

Assuming, i'm right, the issue is gnome-shell sets up a strut where the panels are to tell mutter to avoid overlapping windows with the panels. Anywhere a strut is in place, mutter won't let windows fully occupy.  The problem is the freedesktop specification for struts is sort of "broken by design" in that struts can only be specified as extending from the outer most edges of the users monitors toward the middle.  If you have strut for a panel that's along an interior monitor edge, then the strut will extend all the way through a whole monitor (say the top monitor) and mutter won't let any windows occupy the top monitor.

Two ways to fix this:

1) make mutter be non-compliant with the spec and carve out the top monitor to fix the brokeness in the spec design
2) stop using freedesktop specified struts for the panels.  gnome-shell and mutter run in the same process, so there's no reason to use an external protocol for communicating where the panels are.  we could just use internal API.  (this is different than the old days when metacity and gnome-panel were separate components).

The first is the least amount of code change, but it has the potential to break things that really do want a strut to extend over the whole top monitor.  (say a magnifier maybe?).

Yes I believe that is at least a portion of the behavior that I've been seeing.
 
The other part has to do with moving windows when the lower monitor is set as the one with the panel-like-menu bar on the top. Then you cannot move windows into area on the upper monitor above the menubar which is on the top of the lower monitor. 

I've never been an GUI or X developer but it sounds to me like 2 is a better approach to fixing the problem. Then revise and version the spec through whatever standards process there is for that part of the interface.

I think we need to work out the fix upstream first, before backporting it to RHEL. Moving to 7.1

Then I think it is important to provide a warning dialog or something for people who have a screen layout that won't work with the _DEFAULT_ session preference for RHEL7. We have something very visible that really just doesn't work. This is not a good advertisement for RHEL.

So maybe when a person is in the display configuration dialog, if they select a display arrangement that won't work well with the gnome legacy configuration you pop up a dialog with a warning suggesting that they change to the normal gnome-shell session style rather than the legacy style.