1). How is the system supposed to tell the difference between a mouse click and a mouse drag? [One way would be to assume it is a click but if the mouse is still down after some period of time--half a second? less?--then it converts to a drag. But then the person who wants to drag will feel a hesitation before the drag starts. Another way would be to make it modal: That is, it depends on which TAB is currently active.]
Is this a problem? It somewhat works at the moment using double click to show the menu and click and drag for the map
2). What is the purpose of double click? Why were you worried about implementing it?
Upon implementing a menu to show upon clicking the map, due to this map being a click and drag map, every time you clicked on the map to simply drag it, a new menu should show.
This menu is going to be used for multiple things, but the general menu is to set their current position there, mark the tile as a hotspot for being put into jail or hospital or finding a chest, getting a safe route directions from or to that tile or zooming in/out from that tile.
Some tiles are going to be mission starters, where as in the menu you can view the mission and get help to do it.
Just thought I'd answer these questions first. I'm going to compose a new message after this one to explain the whole thing.