Posted on GDLTalk, but two advices are better than one.
It seems that User interface is not supported with labels on 8.1.
Look at the attached files
Two small pla.files, one for 7 and the other for 8.1
Objects are the same, just updated for 8.1 with the special menu
and saved by subtype.
It is a text object and a text label for comparison. Scripts are quite the same.
With 7, text object and text label work fine.
With 8.1, when i click into the text label UI, AC crashes.
This does not happen with the text object UI.
If i use the window symbol for the label, it's allright.
Same thing if i open the label part and use the User interface.
Problem occurs only in the floor plan window.
Can someone tell me if it is the same for you, or what is wrong?
For me it happens with any User interface into a label.