Double tap on contribution executes two commands

[Matthias Schoettle]

Steps to reproduce:

1. Open a concern's Impact Model
2. Double-tap on an existing contribution

Result:

You should notice that the save and undo buttons are activated and it is possible to undo twice.

There should be no change before the user enters a new contribution. I believe this is due to the possible drag to adjust the contribution value by dragging up or down. However, probably the minimum drag distance is not used.

I suggest to use the DelayedDrag with the constant for minimum drag distance.