Fix objects not selected on right-click

- This is a regression from 78f1d34
- The actual workaround is to set the cursor to null when on Mac and right-clicking
- See #1099
- And tidy up the code

com.archimatetool.editor/src/com/archimatetool/editor/diagram/tools/PanningSelectionExtendedTool.java

@@ -7,39 +7,43 @@
 
 import org.eclipse.gef.tools.PanningSelectionTool;
 
+import com.archimatetool.editor.utils.PlatformUtils;
+
 /**
- * Extend the PanningSelectionTool so that Panning occurs on middle mouse button
+ * Extend the PanningSelectionTool so that panning occurs on middle mouse button
  * 
  * @author Phillip Beauvoir
  */
 public class PanningSelectionExtendedTool extends PanningSelectionTool {
 
     @Override
     protected boolean handleButtonDown(int which) {
-        if(which == 2) {
-            if(stateTransition(STATE_INITIAL, PAN)) {
-                refreshCursor();
-            }
-            which = 1;
+        // Middle mouse button down so set to panning state
+        if(which == 2 && stateTransition(STATE_INITIAL, PAN)) {
+            refreshCursor();
+            return super.handleButtonDown(1); // Set to left mouse
         }
 
         /*
-         * A right-click on the canvas will show the plus cursor for the marquee selection tool.
-         * On macOS Sonoma the current cursor persists onto the context menu.
-         * This is a general problem with Sonoma, see https://github.com/eclipse-platform/eclipse.platform.swt/issues/773
-         * As the right-click is only for showing the context menu we don't need to see this cursor when right-clicking at all, so trap this here.
+         * A right-click on the canvas will briefly show the plus cursor for the marquee selection tool before showing the context menu.
+         * On macOS Sonoma and greater this cursor persists while the context menu is shown.
+         * This is a general problem with Mac, see https://github.com/eclipse-platform/eclipse.platform.swt/issues/773
+         * As right-click is only used for showing the context menu we don't need to see this cursor when right-clicking at all, so trap this here.
          */
-        if(which == 3) {
-            return true;
+        if(PlatformUtils.isMac() && which == 3 || (which == 1 && getCurrentInput().isControlKeyDown())) {
+            boolean result = super.handleButtonDown(which);
+            setCursor(null);
+            return result;
         }
 
         return super.handleButtonDown(which);
     }
 
     @Override
     protected boolean handleButtonUp(int which) {
-        if(which == 2) {
-            which = 1;
+        // Middle mouse button up and panning in progress
+        if(which == 2 && isInState(PAN_IN_PROGRESS)) {
+            return super.handleButtonUp(1);   // Set to left mouse
         }
 
         return super.handleButtonUp(which);