applets/taskmanager: make it harder to accidentally start a drag
Right now there is code to reduce the liklihood of accidental drags, but it suffers from two issues that reduce its effectiveness:
- It doesn't internally check for all the parameters used to signify that the mouse is pressed, just one which serves as a proxy for the rest. As a result, if they get out of sync it's possible for a drag to begin even when the mouse isn't pressed.
- It has a distance threshold before starting a drag that defaults to 10px, but can be overridden in config files to be much less. And 10px is quite small anyway.
This commit fixes those issues by checking for all press-based paremeters when determining whether to start a drag, and and ensuring that the drag threshold never falls below 1/2 of the icon size no matter what it's set to in the config file.
BUG: 402376 FIXED-IN: 5.26