XML timer delay for makemdl part visibility toggle

I'm strugling with a bit of code in makemdl.parts.xml and I am sure there is a simple solution for the problem:What I want to achieve is set a small delay between a mouse click and the toggle of the visibility of another part. In other words, I need the following sequence of events:Part visibleclick2 second delayPart invisibleclick2 second delayPart visibleThe clickable part is hopper_door:hopper_door(L:HOPPER,bool) 100 *30...(L:HOPPER,bool) ! (>L:HOPPER,bool)(P:ABSOLUTE TIME,seconds) (>L:HOPPER TIMER,seconds)...For the part with the visibility constraint (hopper_dark) I've tried variations of the following:hopper_dark(P:ABSOLUTE TIME,seconds) (L:HOPPER TIMER,seconds) - 2 > (L:HOPPER DARK,bool) ! (>L:HOPPER DARK,bool)1But this doesn't work properly (part visibility cycles on every click instead of toggling). Is there a simple way to solve this problem?Thanks!