Enhance Pressing Down Logic of Selection Handle

[Rosemoe]

Currently, the selection handle is considered pressed as long as the user pointer down position is near the handle rectangle. And clicks on the handle are also considered to be moving the selection handle, while sometimes it is actually not.
When is font size is fairly small, the user can unexpectedly move the selection to otherwhere by click because of the handling logic.

We should consider it a normal click instead of moving the selection handle.