Maybe use TempVars if you want to read or set a value regardless of whether or not the form is open? If using tabbed views that will have to be the default, so remove whatever popup and/or modal properties you have set. If you want to open it some other way at times then set the window data mode or form popup/modal property in the opening code. AFAIK, those will override the tab view.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.