Returns or selects the active tab on the window of a WaterExplorer object. If the name configured in this property is invalid, that is, an empty String or a non-existent tab name, a script error is then generated. This property is updated whenever a new tab is selected on the window of a WaterExplorer object. Likewise, if the active tab is removed, by using the RemoveScreenTab method, this property is also updated to reflect the new active tab. Possible values for default tabs are "Analogs" (Analog tab), "Discretes" (Discrete tab), or "Commands" (Commands tab).