Tweak atom and bond removal

Fix #1478
- remove a hydrogen if right-clicked (always)
- adjust hydrogens if you right-click to break a bond

Signed-off-by: Geoff Hutchison <geoff.hutchison@gmail.com>

avogadro/qtplugins/editor/editor.cpp

@@ -73,7 +73,8 @@ Editor::Editor(QObject* parent_)
   m_activateAction->setToolTip(
     tr("Draw Tool \t(%1)\n\n"
        "Left Mouse: \tClick and Drag to create Atoms and Bond\n"
-       "Right Mouse: \tDelete Atom").arg(shortcut));
+       "Right Mouse: \tDelete Atom")
+      .arg(shortcut));
   setIcon();
   reset();
 }
@@ -421,9 +422,9 @@ void Editor::atomRightClick(QMouseEvent* e)
   Core::Array<Index> bondedAtoms;
   if (m_toolWidget->adjustHydrogens()) {
     // before we remove the atom, we need to delete any H atoms
-    // that are bonded to it
+    // that are bonded to it -- unless it's a hydrogen atom itself
     RWAtom atom = m_molecule->atom(m_clickedObject.index);
-    if (atom.isValid()) {
+    if (atom.isValid() && atom.atomicNumber() != Core::Hydrogen) {
       // get the list of bonded atoms
       Core::Array<RWBond> atomBonds = m_molecule->bonds(atom);
       for (const RWBond& bond : atomBonds) {
@@ -453,8 +454,17 @@ void Editor::atomRightClick(QMouseEvent* e)
 void Editor::bondRightClick(QMouseEvent* e)
 {
   e->accept();
-  m_molecule->removeBond(m_clickedObject.index);
-  m_molecule->emitChanged(Molecule::Bonds | Molecule::Removed);
+  // see if we need to adjust hydrogens
+  if (m_toolWidget->adjustHydrogens()) {
+    RWBond bond = m_molecule->bond(m_clickedObject.index);
+    RWAtom atom1 = bond.atom1();
+    RWAtom atom2 = bond.atom2();
+    m_molecule->removeBond(m_clickedObject.index);
+    QtGui::HydrogenTools::adjustHydrogens(atom1);
+    QtGui::HydrogenTools::adjustHydrogens(atom2);
+  }
+  m_molecule->emitChanged(Molecule::Atoms | Molecule::Bonds |
+                          Molecule::Removed);
 }
 
 int expectedBondOrder(RWAtom atom1, RWAtom atom2)