Toolbar customization refinements & fixes

- make ToolbarEditor dialog show the proper names for customisable
  actions / item as previously it was showing the internal tags/ids

- allow for the view mode & page zoom dropdowns to be customised
  like all other toolbar items

- re-ordered the available and chosen lists in the dialogue box to make
  more sense - most specific is now at the right and not in the middle

- Customize Toolbars menu is greyed out / disabled when toolbars are
  not customisable, i.e. because we're in advanced or basic mode or
  because although workspace is editable the toolbars are not

- available actions now maintain STANDARD order when items are removed
  from the current toolbar

- improved the spacing of view mode and page zoom dropdowns on the toolbar

mscore/musescore.cpp

@@ -288,7 +288,10 @@ const std::list<const char*> MuseScore::_allFileOperationEntries {
     "file-save-online",
     "print",
     "undo",
-    "redo"
+    "redo",
+    "",
+    "zoom-options",
+    "view-mode"
 };
 
 const std::list<const char*> MuseScore::_allPlaybackControlEntries {
@@ -1006,46 +1009,63 @@ bool MuseScore::isInstalledExtension(QString extensionId)
 
 void MuseScore::populateFileOperations()
 {
-    // Save the current zoom and view-mode combobox states. if any.
-    const auto magState = mag ? std::make_pair(mag->currentIndex(), mag->currentText()) : std::make_pair(-1, QString());
-    const auto viewModeComboIndex = viewModeCombo ? viewModeCombo->currentIndex() : -1;
+      fileTools->clear();
 
-    fileTools->clear();
+      bool leftToRightLayout = qApp->layoutDirection() == Qt::LayoutDirection::LeftToRight;
 
-    if (qApp->layoutDirection() == Qt::LayoutDirection::LeftToRight) {
-        for (auto s : _fileOperationEntries) {
-            if (!*s) {
-                fileTools->addSeparator();
-            } else {
-                fileTools->addWidget(new AccessibleToolButton(fileTools, getAction(s)));
-            }
-        }
-    } else {
-        _fileOperationEntries.reverse();
-        for (auto s : _fileOperationEntries) {
-            if (!*s) {
-                fileTools->addSeparator();
-            } else {
-                fileTools->addWidget(new AccessibleToolButton(fileTools, getAction(s)));
+      if (!leftToRightLayout)
+            _fileOperationEntries.reverse();
+
+
+      for (auto s : _fileOperationEntries) {
+
+            if (!*s)
+                  fileTools->addSeparator();
+            else if (!strcmp("view-mode", s))
+                  addViewModeWidget();
+            else if (!strcmp("zoom-options", s))
+                  addZoomOptionsWidget();
+            else
+                  fileTools->addWidget(new AccessibleToolButton(fileTools, getAction(s)));
             }
-        }
-        _fileOperationEntries.reverse();
-    }
 
-    // Currently not customizable in ToolbarEditor
-    fileTools->addSeparator();
-    mag = new MagBox;
+      if (!leftToRightLayout)
+            _fileOperationEntries.reverse();
+}
 
-    // Restore the saved zoom combobox index and text, if any.
-    if (magState.first != -1) {
+// zoom-options is treated as a special case as it's not a QToolButton
+// but, rather, a MagBox (a sub-class of QComboBox)
+void MuseScore::addZoomOptionsWidget()
+{
+      // Save the current zoom state, if any.
+      const auto magState = mag ? std::make_pair(mag->currentIndex(), mag->currentText()) : std::make_pair(-1, QString());
+      QWidget* spacer1 = new QWidget();
+      spacer1->setMinimumWidth(1);
+      spacer1->setMaximumWidth(1);
+      fileTools->addWidget(spacer1);
+      mag = new MagBox;
+
+       // Restore the saved zoom combobox index and text, if any.
+      if (magState.first != -1) {
         mag->setCurrentIndex(magState.first);
         mag->setCurrentText(magState.second);
-    }
-
-    connect(mag, SIGNAL(magChanged(MagIdx)), SLOT(magChanged(MagIdx)));
-    fileTools->addWidget(mag);
-
-    viewModeCombo = new QComboBox(this);
+      }
+
+      connect(mag, SIGNAL(magChanged(MagIdx)), SLOT(magChanged(MagIdx)));
+      fileTools->addWidget(mag);
+      QWidget* spacer2 = new QWidget();
+      spacer2->setMinimumWidth(1);
+      spacer2->setMaximumWidth(1);
+      fileTools->addWidget(spacer2);
+}
+
+// view-mode is treated as a special case as it's not a QToolButton
+// but, rather, a QComboBox
+void MuseScore::addViewModeWidget()
+      {
+    // Save the current view-mode combobox state, if any.
+    const auto viewModeComboIndex = viewModeCombo ? viewModeCombo->currentIndex() : -1;
+      viewModeCombo = new QComboBox(this);
 #if defined(Q_OS_MAC)
     viewModeCombo->setFocusPolicy(Qt::StrongFocus);
 #else
@@ -4690,6 +4710,12 @@ void MuseScore::changeState(ScoreState val)
         getAction("split-measure")->setEnabled(cs && cs->masterScore()->excerpts().size() == 0);
     }
 
+    // currentWorkspace can be nullptr in some contexts, so check to avoid crash
+    Workspace* currentWorkspace = WorkspacesManager::currentWorkspace();
+    if (currentWorkspace) {
+            getAction("edit-toolbars")->setEnabled(currentWorkspace->canCustomizeToolbars());
+    }
+
     // disabling top level menu entries does not
     // work for MAC
 

mscore/musescore.h

@@ -835,6 +835,8 @@ public slots:
     std::list<const char*>* fileOperationEntries() { return &_fileOperationEntries; }
     void setFileOperationEntries(std::list<const char*> l) { _fileOperationEntries = l; }
     void populateFileOperations();
+    void addViewModeWidget();
+    void addZoomOptionsWidget();
 
     static const std::list<const char*>& allPlaybackControlEntries() { return _allPlaybackControlEntries; }
     std::list<const char*>* playbackControlEntries() { return &_playbackControlEntries; }