[GTK4] Add missing Callback dispose in Display

Author: jonahgraham

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Display.java

@@ -4688,6 +4688,10 @@ void releaseDisplay () {
 		activateCallback = null;
 		activateProc = 0;
 
+		computeSizeCallback.dispose();
+		computeSizeCallback = null;
+		computeSizeProc = 0;
+
 		gesturePressReleaseCallback.dispose();
 		gesturePressReleaseCallback = null;
 		gesturePressReleaseProc = 0;

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Display.java

@@ -1627,6 +1627,18 @@ public void test_getWarnings() {
 	}
 }
 
+@Test
+public void test_manyDispose() {
+	int i = 0;
+	// We iterate a number slightly bigger than MAX_CALLBACKS
+	// If a single non-static callback isn't disposed then the
+	// callback table will be filled and this test will fail
+	while (i++ < 300) {
+		final Display display = new Display();
+		display.dispose();
+	}
+}
+
 @Test
 public void test_isDisposed() {
 	Display disp = new Display();