Bug 538579 - DateTime SWT.DATE and SWT.Time styles do not allow to set
value

SWT.DATE & SWT.TIME need handle to be registered in widgetTable in order
to
function correctly. Added additional checks to register/deregister
handle.

Tested with attached snippet, no additional test breaks in
AllNonBrowserTests.

Change-Id: I928aa7122abba427af29242504c3a5feeacf141b
Signed-off-by: Xi Yan <xixiyan@redhat.com>
(cherry picked from commit 4637faea28199f85d42a4ca237ad145cd1f2d386)
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/DateTime.java b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/DateTime.java
index a21ebe2..aba0f01 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/DateTime.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/DateTime.java
@@ -1852,6 +1852,7 @@
 @Override
 void register () {
 	super.register ();
+	if (handle != 0 && display.getWidget(handle) == null) display.addWidget(handle, this);
 	if (containerHandle != 0 && containerHandle != handle) display.addWidget (containerHandle, this);
 	if (textEntryHandle != 0 && textEntryHandle != containerHandle) display.addWidget (textEntryHandle, this);
 }
@@ -1864,6 +1865,7 @@
 @Override
 void deregister () {
 	super.deregister ();
+	if (handle != 0 && display.getWidget(handle) != null) display.removeWidget(handle);
 	if (containerHandle != 0 && containerHandle != handle) display.removeWidget (containerHandle);
 	if (textEntryHandle != 0 && textEntryHandle != containerHandle) display.removeWidget (textEntryHandle);
 }
diff --git a/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug538579_DateTimeSetValue.java b/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug538579_DateTimeSetValue.java
new file mode 100644
index 0000000..b1e625d
--- /dev/null
+++ b/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug538579_DateTimeSetValue.java
@@ -0,0 +1,47 @@
+/*******************************************************************************
+ * Copyright (c) 2018 Red Hat and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Red Hat - initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.swt.tests.gtk.snippets;
+
+
+import static org.eclipse.swt.events.SelectionListener.widgetSelectedAdapter;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.layout.RowLayout;
+import org.eclipse.swt.widgets.DateTime;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Shell;
+
+public class Bug538579_DateTimeSetValue {
+
+public static void main (String [] args) {
+	Display display = new Display ();
+	Shell shell = new Shell (display);
+	shell.setLayout (new RowLayout ());
+
+	DateTime date = new DateTime (shell, SWT.DATE);
+	date.addSelectionListener (
+		widgetSelectedAdapter(e -> System.out.println ("Date changed")));
+
+	DateTime time = new DateTime (shell, SWT.TIME);
+	time.addSelectionListener (widgetSelectedAdapter(e -> System.out.println ("time changed")));
+
+	shell.pack ();
+	shell.open ();
+	while (!shell.isDisposed ()) {
+		if (!display.readAndDispatch ()) display.sleep ();
+	}
+	display.dispose ();
+}
+}
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