Interfaces to Xconq have typically two major modes governing how input will be handled; survey mode and move mode. The purpose of these modes is to streamline the input and interaction process; they have no other consequence, and all functionality should be available in either mode.
In survey mode, you are basically just looking around the map. Normal mouse clicks change the focus and perhaps scroll the map, but do not cause any units to do anything.
In move mode, a normal mouse click means to move the currently selected unit or units to the location of the click.