Fix: Docking Called from Shortcut Without Status Bar

When starting a docking operation from an assigned shortcut, the source
area will be incorrect if the Status Bar is not currently being shown.
This PR just adds defaults that are never valid window coordinates.

Pull Request: https://projects.blender.org/blender/blender/pulls/129187

source/blender/editors/screen/screen_ops.cc

@@ -4290,26 +4290,12 @@ static void SCREEN_OT_area_join(wmOperatorType *ot)
   ot->flag = OPTYPE_BLOCKING;
 
   /* rna */
-  RNA_def_int_vector(ot->srna,
-                     "source_xy",
-                     2,
-                     nullptr,
-                     INT_MIN,
-                     INT_MAX,
-                     "Source location",
-                     "",
-                     INT_MIN,
-                     INT_MAX);
-  RNA_def_int_vector(ot->srna,
-                     "target_xy",
-                     2,
-                     nullptr,
-                     INT_MIN,
-                     INT_MAX,
-                     "Target location",
-                     "",
-                     INT_MIN,
-                     INT_MAX);
+  const int def[2] = {-100, -100};
+
+  RNA_def_int_vector(
+      ot->srna, "source_xy", 2, def, INT_MIN, INT_MAX, "Source location", "", INT_MIN, INT_MAX);
+  RNA_def_int_vector(
+      ot->srna, "target_xy", 2, def, INT_MIN, INT_MAX, "Target location", "", INT_MIN, INT_MAX);
 }
 
 /** \} */