Steps to reproduce:
1. Open diagram, insert "Assign" element to diagram
2. Set cursor to "Assign to" and press "Ctrl+Space"
3. Select element from list
At the replaying the test is failed:
Execution failed on line 56 at column 1 (NETSDK-786_TC1_Check document autosave feature when user runs a design_test.test:56)
The Window "[parentClass, CompletionProposalPopup.createProposalSelector()]" could not be found.
This situation is unstable, but sometimes it is reproduced on local machine.