
Bug #1813: Compilation Manager remebers units deleted.
Fixed by change #2816

Bug behaviour: In the Compilation Manager (CM), load any source so that there are 
units displayed in the CM, then select Build->Delete All followed by Build->Read
Dependencies, which then looks for the last unit selected.  True on both Unix and
Windows.

Proper behaviour:  After doing Build->Delete All, the Build->Read Dependencies 
option should be disabled.