osgearth_imgui.exe imgui multiple screen problem

[yunusyurtturk]

Hi, I updated my code to osgEarth-3.7 from a previous version after formatting my computer.
After the update, I wasn't able to see ImGui panels in my application, then I tried osgearth_imgui.exe if it works. I realized that ImGui panels are not also rendered.

I'm using 2 monitor setup.
The problem fixed after I add:
viewer.setUpViewOnSingleScreen();

Now they are rendered. You may want to check.

[gwaldron]

I pushed a patch for this in c6b4e56. Thanks.