Once in a while (too often actually) when I want to select an element, I move the element by mistake.
I don’t know how you should solve it, but ForeUI is maybe a bit too sensitive. Maybe a short delay could be implemented to make ForeUI ignore mouse-movements in the very first milliseconds after the mouse click…
Maybe my mouse sensitivity is set to high for ForeUI, but I don’t have the same problem in e.g. Abobe Photoshop and Abobe Flash.