Adding NRE checks and preventing double event subscribing

3 files changed, 24 insertions, 13 deletions

diff --git a/Xwt.Gtk/Xwt.GtkBackend/ButtonBackend.cs b/Xwt.Gtk/Xwt.GtkBackend/ButtonBackend.cs
index e0ab8e77..71c80ff4 100644
--- a/Xwt.Gtk/Xwt.GtkBackend/ButtonBackend.cs
+++ b/Xwt.Gtk/Xwt.GtkBackend/ButtonBackend.cs
@@ -130,6 +130,8 @@ namespace Xwt.GtkBackend
 			if (image.Backend != null)
 				imageWidget = new ImageBox (ApplicationContext, image.WithDefaultSize (Gtk.IconSize.Button));
 
+			labelWidget.Realized -= HandleStyleUpdate;
+			labelWidget.StyleSet -= HandleStyleUpdate;
 			labelWidget = null;
 
 			if (label != null && imageWidget == null) {
@@ -209,6 +211,8 @@ namespace Xwt.GtkBackend
 				Widget.Label = null;
 				Widget.Image = labelWidget;
 			}
+			labelWidget.Realized -= HandleStyleUpdate;
+			labelWidget.StyleSet -= HandleStyleUpdate;
 
 			formattedText = label;
 			labelWidget.ApplyFormattedText (formattedText);
@@ -252,7 +256,7 @@ namespace Xwt.GtkBackend
 
 		public void SetFormattedText (FormattedText text)
 		{
-			SetContent (text.Text, Widget.UseUnderline, this.image, ContentPosition.Center);
+			SetContent (text?.Text, Widget.UseUnderline, this.image, ContentPosition.Center);
 			SetFormattedContent (text, ContentPosition.Center);
 		}
 
@@ -310,9 +314,10 @@ namespace Xwt.GtkBackend
 
 		protected override void Dispose (bool disposing)
 		{
-			if (labelWidget != null) {
+			if (disposing && labelWidget != null) {
 				labelWidget.Realized -= HandleStyleUpdate;
 				labelWidget.StyleSet -= HandleStyleUpdate;
+				labelWidget = null;
 			}
 			base.Dispose (disposing);
 		}
diff --git a/Xwt.Gtk/Xwt.GtkBackend/MenuItemBackend.cs b/Xwt.Gtk/Xwt.GtkBackend/MenuItemBackend.cs
index 5633b937..2f8af07c 100644
--- a/Xwt.Gtk/Xwt.GtkBackend/MenuItemBackend.cs
+++ b/Xwt.Gtk/Xwt.GtkBackend/MenuItemBackend.cs
@@ -172,11 +172,14 @@ namespace Xwt.GtkBackend
 		FormattedText formattedText = null;
 		public void SetFormattedText (FormattedText text)
 		{
-			label.Text = text.Text;
+			label.Text = text?.Text;
 			formattedText = text;
+			label.Realized -= HandleStyleUpdate;
+			label.StyleSet -= HandleStyleUpdate;
+			label.ApplyFormattedText(text);
 			label.Realized += HandleStyleUpdate;
 			label.StyleSet += HandleStyleUpdate;
-			label.ApplyFormattedText(text);
+
 		}
 
 		void HandleStyleUpdate (object sender, EventArgs e)
@@ -273,6 +276,7 @@ namespace Xwt.GtkBackend
 			if (label != null) {
 				label.Realized -= HandleStyleUpdate;
 				label.StyleSet -= HandleStyleUpdate;
+				label = null;
 			}
 		}
 	}
diff --git a/Xwt.Gtk/Xwt.GtkBackend/Util.cs b/Xwt.Gtk/Xwt.GtkBackend/Util.cs
index 3b12e967..e4bb7010 100644
--- a/Xwt.Gtk/Xwt.GtkBackend/Util.cs
+++ b/Xwt.Gtk/Xwt.GtkBackend/Util.cs
@@ -284,16 +284,18 @@ namespace Xwt.GtkBackend
 		internal static void ApplyFormattedText(this Gtk.Label label, FormattedText text)
 		{
 			var list = new FastPangoAttrList ();
-			if (label.IsRealized) {
-				var color = Gdk.Color.Zero;
-				var colorVal = label.StyleGetProperty ("link-color");
-				if (colorVal is Gdk.Color)
-					color = (Gdk.Color)colorVal;
-				if (!color.Equals (Gdk.Color.Zero))
-					list.DefaultLinkColor = color;
+			if (text != null) {
+				if (label.IsRealized) {
+					var color = Gdk.Color.Zero;
+					var colorVal = label.StyleGetProperty ("link-color");
+					if (colorVal is Gdk.Color)
+						color = (Gdk.Color)colorVal;
+					if (!color.Equals (Gdk.Color.Zero))
+						list.DefaultLinkColor = color;
+				}
+				var indexer = new TextIndexer (text.Text);
+				list.AddAttributes (indexer, text.Attributes);
 			}
-			var indexer = new TextIndexer (text.Text);
-			list.AddAttributes (indexer, text.Attributes);
 			gtk_label_set_attributes (label.Handle, list.Handle);
 		}
 	}