After undo, method output and display box can not be reconnected

[seanycz]

For example, connect String length() with a display box, after update then undo. It can not be reconnected again.

[seanycz]

In Console, it shows "empty redo stack"

[CVIllustrious]

Cannot reproduce the bug

[chenggong03]

@seanycz can you reproduce the bug next time? Maybe it is somehow fixed