Allow reverting of tab content

Adds UI logic to allow reverting of tab content by pressing Ctrl-Shift-R
or by clicking the 'Revert' SimpleAction menu item on the EditorHeader
menu that opens from the upside-down triangle that's on the right edge
of the tabs bar of the IDE.

Similar to arduino#5345 but option is
added to the tabs bar menu and for better clarity is called 'Revert' not
'Refresh'.

Author: maratbn

Diff for: app/src/processing/app/Editor.java

@@ -1867,6 +1867,60 @@ public void updateTitle() {
   }
 
 
+  /**
+   * Handles the user pressing Ctrl-Shift-R or clicking the Revert SimpleAction
+   * menu item on the EditorHeader menu that opens from the upside-down
+   * triangle that's on the right edge of the tabs bar of the IDE, which
+   * reverts / reloads the file in the current tab.
+   */
+  public void handleRevertTab() {
+
+    EditorTab tab = getCurrentTab();
+    if (tab == null) {
+      throw new IllegalStateException();
+    }
+
+    SketchFile fileInTab = tab.getSketchFile();
+    if (fileInTab == null) {
+      throw new IllegalStateException();
+    }
+
+    // As of Processing 1.0.10, this always happens immediately.
+    // http://dev.processing.org/bugs/show_bug.cgi?id=1456
+
+    toFront();
+
+    if (!fileInTab.fileExists()) {
+      JOptionPane.showMessageDialog(
+                      this,
+                      I18n.format(
+                        tr("Unable to revert \"{0}\" as it does not exist."),
+                        fileInTab.getFileName()),
+                      tr("Unable to Revert"),
+                      JOptionPane.ERROR_MESSAGE);
+      return;
+    }
+
+    String prompt = I18n.format(
+                      sketch.isModified()
+                        ? tr("Modifications detected to \"{0}\".  Revert anyway?")
+                        : tr("Revert \"{0}\"?"),
+                      fileInTab.getFileName());
+
+    int result =  JOptionPane.showConfirmDialog(this, prompt, tr("Revert"),
+                                                JOptionPane.OK_CANCEL_OPTION,
+                                                JOptionPane.QUESTION_MESSAGE);
+
+    switch (result) {
+      case JOptionPane.CANCEL_OPTION:  // Cancel clicked
+      case JOptionPane.CLOSED_OPTION:  // Escape key pressed
+        return;
+    }
+
+    tab.reload();
+  }
+
+
   /**
    * Actually handle the save command. If 'immediately' is set to false,
    * this will happen in another thread so that the message area

Diff for: app/src/processing/app/EditorHeader.java

@@ -94,6 +94,10 @@ public class Actions {
     public final Action renameTab = new SimpleAction(tr("Rename"),
         () -> editor.getSketchController().handleRenameCode());
 
+    public final Action revertTab = new SimpleAction(tr("Revert"),
+        Keys.ctrlShift(KeyEvent.VK_R),
+        () -> editor.handleRevertTab());
+
     public final Action deleteTab = new SimpleAction(tr("Delete"), () -> {
       try {
         editor.getSketchController().handleDeleteCode();
@@ -113,6 +117,7 @@ public class Actions {
       // Normally, this happens automatically for any actions bound to menu
       // items, but only for menus attached to a window, not for popup menus.
       Keys.bind(EditorHeader.this, newTab);
+      Keys.bind(EditorHeader.this, revertTab);
       Keys.bind(EditorHeader.this, prevTab);
       Keys.bind(EditorHeader.this, nextTab);
 
@@ -315,6 +320,7 @@ public void rebuildMenu() {
 
     menu.add(new JMenuItem(actions.newTab));
     menu.add(new JMenuItem(actions.renameTab));
+    menu.add(new JMenuItem(actions.revertTab));
     menu.add(new JMenuItem(actions.deleteTab));
     menu.addSeparator();
     menu.add(new JMenuItem(actions.prevTab));