I resolved another minor mystery recently after a question from a customer. It has to do with the behavior of variables whenever you open a new tab by doing a drill-down on a group. The same thing can happen when you double click on a subreport in preview mode to open the preview of that subreport.

What I had seen was that some variables would carry to the new tab others would reset to zero/blank. So when a customer explained that this was causing a problem in their report I did some digging and experimenting. I discovered that this problem only occurs with shared variables, which pass to and from subreports. Shared variables will not carry from the preview into the new tab, while default (global) variables carry just fine.

I did some more digging to find a workaround and only found a partial one. I say partial because it will work for group drill-downs but not subreport drill-downs.  If you drill down on a group, typically you will see the Group Header, the Group Footer and the details for that group. The workaround is to make a second copy of the subreport that generates the shared variable, and put it into the group header of that group. To make sure that subreport doesn’t run repeatedly you can either hide the group header, or suppress the subreport with a condition like this one:

DrillDownGroupLevel = 0

Either of these will keep the extra subreport from firing until you do the drill-down. Then one instance of the subreport will run inside the drill-down and the shared variable will carry to the details and group footer inside that drill-down tab.

The downsides are

1) The subreport will have to run again if you do another a drill-down.

2) It won’t work for a subreport because you can’t put one subreport inside another.

If you have any questions about using variables, call to schedule a session.

Added 4/2/2023 – Another solution, if you are willing to use a third party dll, is to use the “Key-Value pair” functionality in CUT Light. This allows you to “Set” and “Get” values that are independent of the report’s variable process, so they aren’t reset by the drill-down.
https://www.milletsoftware.com/CUT_Light_User_Manual/#uflLookupGetEntry()