Add availableScreenRect(int id) to Corona base class

This is already implemented in ShellCorona and is quite handy too

Reviewed-by: Marco Martin

src/plasma/corona.cpp

@@ -219,6 +219,11 @@ QRegion Corona::availableScreenRegion(int id) const
     return QRegion(screenGeometry(id));
 }
 
+QRect Corona::availableScreenRect(int id) const
+{
+    return screenGeometry(id);
+}
+
 void Corona::loadDefaultLayout()
 {
     //Default implementation does nothing

src/plasma/corona.h

@@ -124,6 +124,19 @@ public:
      */
     virtual QRegion availableScreenRegion(int id) const;
 
+    /**
+     * Returns the available rect for a given screen.
+     * The difference between this and availableScreenRegion()
+     * is that this method returns only a rectangular
+     * available space (it doesn't care if your panel is not 100% width).
+     * The available rect excludes panels and similar windows.
+     * Valid screen ids are 0 to numScreens()-1.
+     * By default this method returns a rectangular region
+     * equal to screenGeometry(id); subclasses that need another
+     * behavior should override this method.
+     */
+    virtual QRect availableScreenRect(int id) const;
+
     /**
      * This method is useful in order to retrieve the list of available
      * screen edges for panel type containments.
@@ -231,6 +244,11 @@ Q_SIGNALS:
      */
     void availableScreenRegionChanged();
 
+    /**
+     * This signal indicates that a change in available screen gemetry occurred.
+     */
+    void availableScreenRectChanged();
+
     /**
      * emitted when immutability changes.
      * this is for use by things that don't get constraints events, like plasmaapp.