The current implementation of drag & drop makes Mage's Maze unwinnable in Quest for Glory 1 (VGA remake, not sure about the original). The reason is that the first tap results in a single click signal, rendering the Fetch spell impossible to use.
Suggestion: give the player some means to switch between tap -> mouse move (the current M.O) and tap -> click / hold+move -> drag mode, since the various different games supported by scummvm have very different controls.
If there's time, as an added convenience for stylus users, I suggest binding stylus depress+button hold to drag. This would make it easy to drag anywhere it is needed without dispatching a ghost click first.