Constructive correction workaround for blank viewer window on macOS

[markcmiller86]

Describe the bug

On macOS, many users have reported that when they go to plot something, the viewer window remains blank as when VisIt first launched but that something cuasing a refresh (e.g. resize, maybe right click to reveal pull down menu) triggers everything to display.

This issue is about finding a simple bit of code injection somewhere in the viewer that causes this to happen automagically as a precaution against this continuing to happen. It should probably be restricted to occur only on macOS.

This would be a constructive correction until we can fully resolve the issue.