Trying to improve "grab" behavior of partial selection

Problem was: with a partial selection, clicking
in the vicinity of a non-selected edge could
make this edge the selected one. So it was
not possible to drag the selection in some
cases.

With "move mode" it was. The difference was in
the detection logic that decides where a click
is on the selection or outside.

Now, the logic is aligned, and partial mode
clicks will check whether the mouse pointer
is inside the selection bbox (plus some
margin). In that case, the click applies to
the current selection.

src/edt/edt/edtPartialService.cc

@@ -1182,6 +1182,19 @@ PartialService::timeout ()
   mp_view->clear_transient_selection ();
   clear_mouse_cursors ();
 
+  double le = catch_distance () * 3.0;  //  see Editables::selection_catch_bbox()
+  db::DBox sel_catch_box = selection_bbox ().enlarged (db::DVector (le, le));
+  if (has_selection () && sel_catch_box.contains (m_hover_point)) {
+
+    //  no transient selection if inside current selection - if we click there, we catch the
+    //  currently selected objects
+    resize_markers (0, true);
+    resize_inst_markers (0, true);
+
+    return;
+
+  }
+
   //  compute search box
   double l = catch_distance ();
   db::DBox search_box = db::DBox (m_hover_point, m_hover_point).enlarged (db::DVector (l, l));
@@ -2035,45 +2048,13 @@ PartialService::mouse_click_event (const db::DPoint &p, unsigned int buttons, bo
     //  select is allowed to throw an exception 
     try {
 
-      //  compute search box
-      double l = catch_distance ();
-      db::DBox search_box = db::DBox (p, p).enlarged (db::DVector (l, l));
-
-      //  check, if there is a selected shape under the mouse - in this case, we do not do a new selection
-      PartialShapeFinder finder (true /*point mode*/, m_top_level_sel, db::ShapeIterator::All);
-      finder.find (view (), search_box);
-
-      //  check, if there is a selected shape under the mouse - in this case, we do not do a new selection
-      lay::InstFinder inst_finder (true /*point mode*/, m_top_level_sel, true /*full arrays*/, true /*enclose*/, 0 /*no excludes*/, true /*visible layers*/);
-      inst_finder.find (view (), search_box);
-
-      //  collect the founds from the finder
-      //  consider a new selection if new objects are selected or the current selection is shape-only 
-      //  (this may happen if points have been inserted)
-      bool new_selection = ((finder.begin () == finder.end () && inst_finder.begin () == inst_finder.end ()) 
-                             || mode != lay::Editable::Replace);
-
-      for (PartialShapeFinder::iterator f = finder.begin (); f != finder.end () && ! new_selection; ++f) {
-        partial_objects::const_iterator sel = m_selection.find (f->first);
-        new_selection = true;
-        if (sel != m_selection.end ()) {
-          for (std::vector<edt::EdgeWithIndex>::const_iterator e = f->second.begin (); e != f->second.end () && new_selection; ++e) {
-            if (sel->second.find (*e) != sel->second.end ()) {
-              new_selection = false;
-            }
-          }
-        }
-      }
-
-      if (finder.begin () == finder.end ()) {
-
-        for (lay::InstFinder::iterator f = inst_finder.begin (); f != inst_finder.end () && ! new_selection; ++f) {
-          partial_objects::const_iterator sel = m_selection.find (*f);
-          if (sel == m_selection.end ()) {
-            new_selection = true;
-          }
-        }
+      bool new_selection = true;
 
+      double le = catch_distance () * 3.0;  //  see Editables::selection_catch_bbox()
+      db::DBox sel_catch_box = selection_bbox ().enlarged (db::DVector (le, le));
+      if (mode == lay::Editable::Replace && has_selection () && sel_catch_box.contains (p)) {
+        //  drag current selection
+        new_selection = false;
       }
 
       if (new_selection) {
@@ -2082,6 +2063,18 @@ PartialService::mouse_click_event (const db::DPoint &p, unsigned int buttons, bo
           m_selection.clear ();
         }
 
+        //  compute search box
+        double l = catch_distance ();
+        db::DBox search_box = db::DBox (p, p).enlarged (db::DVector (l, l));
+
+        //  identify the edges under the mouse
+        PartialShapeFinder finder (true /*point mode*/, m_top_level_sel, db::ShapeIterator::All);
+        finder.find (view (), search_box);
+
+        //  identify the instances under the mouse
+        lay::InstFinder inst_finder (true /*point mode*/, m_top_level_sel, true /*full arrays*/, true /*enclose*/, 0 /*no excludes*/, true /*visible layers*/);
+        inst_finder.find (view (), search_box);
+
         //  clear the selection if we now select a guiding shape or if it was consisting of a guiding shape before
         //  (that way we ensure there is only a guiding shape selected)
         PartialShapeFinder::iterator f0 = finder.begin ();