There is a bit of a rendering delay when XDG first loads -- that's documented and understood.  However, I'm trying to account for a discrepancy when the same, empty grid loads in a popup from a button, versus from a command -- each behaves differently.  I've attached a simple demo app, and your help is appreciated.

If you start the main window, and click the Find command in the menu, notice how the window loads and the grid appears slightly afterwards.  Close the main window and restart it (you must do this each time for first load comparison).  After restart click the large "Find" button, and notice how the window loads intact, grid included, after perhaps a slightly longer delay, not certain.  Both command and button invoke the same code.  I need the latter behavior in my command.  I suspect it has something to do with resource loading, but I'm beyond my knowledge of WPF here.