set Location of menu wrt Display coordinate system

This commit contributes to scaling of the point used to set location of
a menu bar in a display coordinate space hence the scaling methods used
for such Points must be the ones used for Display coordinate system.

contributes to eclipse-platform#62 and eclipse-platform#127

Author: amartya4256

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Menu.java

@@ -1188,9 +1188,7 @@ public void setEnabled (boolean enabled) {
  * </ul>
  */
 public void setLocation (int x, int y) {
-	checkWidget ();
-	int zoom = getZoom();
-	setLocationInPixels(DPIUtil.scaleUp(x, zoom), DPIUtil.scaleUp(y, zoom));
+	setLocation(new Point(x, y));
 }
 
 void setLocationInPixels (int x, int y) {
@@ -1227,7 +1225,7 @@ void setLocationInPixels (int x, int y) {
 public void setLocation (Point location) {
 	checkWidget ();
 	if (location == null) error (SWT.ERROR_NULL_ARGUMENT);
-	location = DPIUtil.scaleUp(location, getZoom());
+	location = getDisplay().translateLocationInPixelsInDisplayCoordinateSystem(location.x, location.y);
 	setLocationInPixels(location.x, location.y);
 }
 

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Widget.java

@@ -1651,8 +1651,8 @@ boolean showMenu (int x, int y) {
 
 boolean showMenu (int x, int y, int detail) {
 	Event event = new Event ();
-	int zoom = getZoom();
-	event.setLocation(DPIUtil.scaleDown(x, zoom), DPIUtil.scaleDown(y, zoom));
+	Point mappedLocation = getDisplay().translateLocationInPointInDisplayCoordinateSystem(x, y);
+	event.setLocation(mappedLocation.x, mappedLocation.y);
 	event.detail = detail;
 	if (event.detail == SWT.MENU_KEYBOARD) {
 		updateMenuLocation (event);
@@ -1663,7 +1663,7 @@ boolean showMenu (int x, int y, int detail) {
 	if (!event.doit) return true;
 	Menu menu = getMenu ();
 	if (menu != null && !menu.isDisposed ()) {
-		Point locInPixels = DPIUtil.scaleUp(event.getLocation(), zoom); // In Pixels
+		Point locInPixels = DPIUtil.scaleUp(event.getLocation(), getZoom()); // In Pixels
 		if (x != locInPixels.x || y != locInPixels.y) {
 			menu.setLocation (event.getLocation());
 		}