Trim problem in xPCB Layout VX.1.1

As shown below,selectaLINEandArc,Trimtoolbarbutton is disabled. But ifthe leftstretchedLINEendpoint, theTrimbuttonisactivated. Theproblem is notevery time, in some casesthere will be, butI still have notfoundthe lawappears.
ProblemsPCBfilein the attachment

Thank you!