therzok

We have some glue code to workaround lack of retina/hidpi support in gtk+.

Yes, having Gtk UI running on Gtk 3 is something we want to have at some point.

Visual Studio for Mac's shell code is written in gtk+ 2. We have supporting code in gtk+ to allow mixing gtk widgets with native widgets.

But the glue code isn't used here, because there is another interesting mechanism at play. The root window created by gtk on macOS is actually an NSWindow (see GdkQuartzWindow), thus you can use Cocoa APIs on the window. We just set the title visibility to hidden and set the native titlebar widget.

Visual Studio for Mac requires OSX 10.11+.

Do you have macOS at least 10.11?