This seemed to work:
if (ActiveDrawing != null)
Sheet swSheet = ActiveDrawing.GetCurrentSheet();
string strSheetName = swSheet.GetName();
But the view remains active in the SolidWorks UI.
after activating the sheet, you may need to select it with:
swDoc.Extension.SelectByID2(strSheetName, "SHEET", 0, 0, 0, false, 0, null, 0);
I realize this is kind of an old post, but I had the same question. I figured out a way to deselect the view this morning on accident.
If you do a force rebuild it deselects any view that is currently active.
Hopes this helps someone.