tdf#97247 Keep focus on merged cell at top-left corner

... when typing either UP or LEFT key.

Change-Id: I7bc0e7eb0cba322bcc26c35d0474ea558d3bdd6e
Reviewed-on: https://gerrit.libreoffice.org/21599Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>

sc/source/ui/view/tabview3.cxx

@@ -1067,6 +1067,17 @@ void ScTabView::MoveCursorRel( SCsCOL nMovX, SCsROW nMovY, ScFollowMode eMode,
         nCurY = (nMovY != 0) ? nOldY+nMovY : (SCsROW) aViewData.GetOldCurY();
     }
 
+    if (nMovX < 0 && nOldX == 0)
+    { // trying to go left from 1st column
+        if (nMovY == 0) // done, because no vertical move is requested
+            return;
+    }
+    if (nMovY < 0 && nOldY == 0)
+    { // trying to go up from 1st row
+        if (nMovX == 0) // done, because no horizontal move is requested
+            return;
+    }
+
     aViewData.ResetOldCursor();
 
     if (nMovX != 0 && ValidColRow(nCurX,nCurY))