Fix "switch mode" to edit current code in new mode when compatible.

app/src/processing/app/Base.java

@@ -607,13 +607,30 @@ public class Base {
         Base.showWarning("Save",
                          "Please save the sketch before changing the mode.",
                          null);
+        return;
+      }
+      nextMode = mode;
+
+      // If the current editor contains file extensions that the new mode can handle, then
+      // write a sketch.properties file with the new mode specified, and reopen.
+      boolean newModeCanHandleCurrentSource = true;
+      for (final SketchCode code: sketch.getCode()) {
+        if (!mode.validExtension(code.getExtension())) {
+          newModeCanHandleCurrentSource = false;
+          break;
+        }
+      }
+      if (newModeCanHandleCurrentSource) {
+        final File props = new File(sketch.getCodeFolder(), "sketch.properties");
+        saveModeSettings(props, nextMode);
+        handleClose(activeEditor, LastEditorClosePolicy.DO_NOT_QUIT);
+        handleOpen(sketch.getMainFilePath());
       } else {
         // If you're changing modes, and there's nothing in the current sketch, you probably
         // don't intend to keep the old, wrong-mode editor around.
         if (sketch.isUntitled()) {
-          handleClose(activeEditor, true);
+          handleClose(activeEditor, LastEditorClosePolicy.DO_NOT_QUIT);
         }
-        nextMode = mode;
         handleNew();
       }
     }
@@ -729,15 +746,7 @@ public class Base {
       }
 
       // Create sketch properties.
-      final File sketchProps = new File(newbieDir, "sketch.properties");
-      try {
-        final Settings settings = new Settings(sketchProps);
-        settings.set("mode", nextMode.getTitle());
-        settings.set("mode.id", nextMode.getIdentifier());
-        settings.save();
-      } catch (IOException e) {
-        System.err.println("While creating " + sketchProps + ": " + e.getMessage());
-      }
+      saveModeSettings(new File(newbieDir, "sketch.properties"), nextMode);
 
       String path = newbieFile.getAbsolutePath();
       /*Editor editor =*/ handleOpen(path, true);
@@ -749,6 +758,18 @@ public class Base {
     }
   }
 
+  // Create or modify a sketch.proprties file to specify the given Mode.
+  private void saveModeSettings(final File sketchProps, final Mode mode) {
+    try {
+      final Settings settings = new Settings(sketchProps);
+      settings.set("mode", mode.getTitle());
+      settings.set("mode.id", mode.getIdentifier());
+      settings.save();
+    } catch (IOException e) {
+      System.err.println("While creating " + sketchProps + ": " + e.getMessage());
+    }
+  }
+
 
 //  /**
 //   * Replace the sketch in the current window with a new untitled document.
@@ -1053,13 +1074,16 @@ public class Base {
     return null;
   }
 
-
+  enum LastEditorClosePolicy {
+    QUIT, DO_NOT_QUIT
+  }
+  
   /**
    * Close a sketch as specified by its editor window.
    * @param editor Editor object of the sketch to be closed.
    * @return true if succeeded in closing, false if canceled.
    */
-  public boolean handleClose(Editor editor, boolean modeSwitch) {
+  public boolean handleClose(Editor editor, LastEditorClosePolicy closePolicy) {
     // Check if modified
 //    boolean immediate = editors.size() == 1;
     if (!editor.checkModified()) {
@@ -1116,7 +1140,7 @@ public class Base {
       Preferences.save();
 
       if (defaultFileMenu == null) {
-        if (modeSwitch) {
+        if (closePolicy == LastEditorClosePolicy.DO_NOT_QUIT) {
           // need to close this editor, ever so temporarily
           editor.setVisible(false);
           editor.dispose();

app/src/processing/app/Editor.java

@@ -22,6 +22,7 @@
 
 package processing.app;
 
+import processing.app.Base.LastEditorClosePolicy;
 import processing.app.contrib.ToolContribution;
 import processing.app.syntax.*;
 import processing.app.tools.*;
@@ -126,7 +127,7 @@ public abstract class Editor extends JFrame implements RunnerListener {
     // add listener to handle window close box hit event
     addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
-          base.handleClose(Editor.this, false);
+          base.handleClose(Editor.this, LastEditorClosePolicy.QUIT);
         }
       });
     // don't close the window when clicked, the app will take care
@@ -601,7 +602,7 @@ public abstract class Editor extends JFrame implements RunnerListener {
     item = Toolkit.newJMenuItem("Close", 'W');
     item.addActionListener(new ActionListener() {
       public void actionPerformed(ActionEvent e) {
-        base.handleClose(Editor.this, false);
+        base.handleClose(Editor.this, LastEditorClosePolicy.QUIT);
       }
     });
     fileMenu.add(item);

app/src/processing/app/Sketch.java

@@ -23,6 +23,7 @@
 
 package processing.app;
 
+import processing.app.Base.LastEditorClosePolicy;
 import processing.core.*;
 
 import java.awt.*;
@@ -569,7 +570,7 @@ public class Sketch {
         // make a new sketch, and i think this will rebuild the sketch menu
         //editor.handleNewUnchecked();
         //editor.handleClose2();
-        editor.base.handleClose(editor, false);
+        editor.base.handleClose(editor, LastEditorClosePolicy.QUIT);
 
       } else {
         // delete the file