show a warning that MW will continue running

gui/griffon-app/controllers/com/muwire/gui/CloseWarningController.groovy

@@ -0,0 +1,39 @@
+package com.muwire.gui
+
+import griffon.core.artifact.GriffonController
+import griffon.core.controller.ControllerAction
+import griffon.inject.MVCMember
+import griffon.metadata.ArtifactProviderFor
+import javax.annotation.Nonnull
+
+@ArtifactProviderFor(GriffonController)
+class CloseWarningController {
+    @MVCMember @Nonnull
+    CloseWarningModel model
+    @MVCMember @Nonnull
+    CloseWarningView view
+
+    UISettings settings
+    File home
+    
+
+    void mvcGroupInit(Map<String, String> args) {
+        model.closeWarning = settings.closeWarning
+    }    
+    
+    @ControllerAction
+    void close() {
+        boolean showWarning = !view.checkbox.model.isSelected()
+        model.closeWarning = showWarning
+        settings.closeWarning = showWarning
+        
+        File props = new File(home, "gui.properties")
+        props.withOutputStream { 
+            settings.write(it)
+        }
+        
+        view.dialog.setVisible(false)
+        view.mainFrame.setVisible(false)
+        mvcGroup.destroy()
+    }
+}