The problem with double-clicking is that some of the items are just too small on a PPC screen. Even with the current operation, when you know an object is there (and have walked to it!), picking it up by clicking on 'pickup' and then tapping the object can be difficult.
Example [SPOILER] : The dime in the pay-phone in DOTT is only a few pixels big. Getting it with the current method is difficult (it took me a couple of tries) but clicking twice, quite fast to within a few very small pixels accuracy will be nigh on impossible.
My suggested method is, I believe, a slight variation on that already discussed:
Single tap - default 'walk to'.
Tap and hold becomes a virtual cursor - you can then sweep the screen to your heart's content. A button then acts as a left click, another as a right click. Taking the stylus off the screen does not act as a left-click. I have found it annoying that after sweeping for an item and pinpointing it, I have taken the stylus off the screen and the character has walked to the item - sometimes obscuring it - before I can click on the pick-up/use/whatever command
Superb job by the way. Don't suppose you can finish polishing it by this time next week so that I can play DOTT in all its glory on a plane trip to France?
Steve