Before all I want to thank Mike for this piece of software. I want to suggest to fire the map viewer through a simple clik from the tray icon instead right click on the tray icon and select it. That means to put an option more in the left single click action or double single click action in the tray icon options :D/
I agree. Perhaps this could be in the tray icon “single click / double click” choice of actions.
Which map do you picture opening in the Map Viewer?
the one in the map history
The map I have in the map history 
A selected map from map history would be fine.
Either that or be able to enter a specific map URL.
Or a relative map in Map History, for example the top one or bottom one, oldest or most recent, or a specific number 1-6.