avoid adjusting position if selected row is visible

https://anki.tenderapp.com/discussions/beta-testing/1868-anki-2124-beta#comment_48227037

qt/aqt/browser.py

@@ -255,9 +255,14 @@ class DataModel(QAbstractTableModel):
         idx = focusedIdx or firstIdx
         tv = self.browser.form.tableView
         if idx:
-            tv.selectRow(idx.row())
+            row = idx.row()
+            pos = tv.rowViewportPosition(row)
+            visible = pos >= 0 and pos < tv.viewport().height()
+            tv.selectRow(row)
+
             # we save and then restore the horizontal scroll position because
             # scrollTo() also scrolls horizontally which is confusing
+            if not visible:
                 h = tv.horizontalScrollBar().value()
                 tv.scrollTo(idx, tv.PositionAtCenter)
                 tv.horizontalScrollBar().setValue(h)