From 671366cd56e7d6b2a2afb0839e7fb0f895cb2df3 Mon Sep 17 00:00:00 2001
From: jpbruyere <jp.bruyere@hotmail.com>
Date: Wed, 21 Oct 2015 12:03:07 +0200
Subject: [PATCH] reset scrollX and Y when scroller child is group and it's
 children have been cleared

---
 src/GraphicObjects/Group.cs    |  5 +++++
 src/GraphicObjects/Scroller.cs | 33 +++++++++++++++++++++++++++------
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/src/GraphicObjects/Group.cs b/src/GraphicObjects/Group.cs
index 78378aa8..bf04617d 100644
--- a/src/GraphicObjects/Group.cs
+++ b/src/GraphicObjects/Group.cs
@@ -19,6 +19,10 @@ namespace go
 		}
 		#endregion
 
+		#region EVENT HANDLERS
+		public event EventHandler<EventArgs> ChildrenCleared;
+		#endregion
+
         bool _multiSelect = false;
 		List<GraphicObject> children = new List<GraphicObject>();
 
@@ -63,6 +67,7 @@ namespace go
 				Children.Remove(g);				
 			}
 			this.RegisterForLayouting ((int)LayoutingType.Sizing);
+			ChildrenCleared.Raise (this, new EventArgs ());
 		}
 		public void putWidgetOnTop(GraphicObject w)
 		{
diff --git a/src/GraphicObjects/Scroller.cs b/src/GraphicObjects/Scroller.cs
index b0fdc120..8c2303cc 100644
--- a/src/GraphicObjects/Scroller.cs
+++ b/src/GraphicObjects/Scroller.cs
@@ -105,20 +105,41 @@ namespace go
 		#region GraphicObject Overrides
 		void OnChildLayoutChanges (object sender, LayoutChangeEventArgs arg)
 		{
+			int maxScroll = MaximumScroll;
 			if (_verticalScrolling) {
-				if (arg.LayoutType  == LayoutingType.Height)
-					ValueChanged.Raise(this, new ValueChangeEventArgs("MaximumScroll", MaximumScroll));				
-			}else if (arg.LayoutType  == LayoutingType.Width)
-				ValueChanged.Raise(this, new ValueChangeEventArgs("MaximumScroll", MaximumScroll));				
+				if (arg.LayoutType == LayoutingType.Height) {
+					if (maxScroll < ScrollY) {
+						Debug.WriteLine ("scrolly={0} maxscroll={1}", ScrollY, maxScroll);
+						ScrollY = 0;
+					}
+					ValueChanged.Raise (this, new ValueChangeEventArgs ("MaximumScroll", maxScroll));
+				}
+			} else if (arg.LayoutType == LayoutingType.Width) {
+				if (maxScroll < ScrollX)
+					ScrollX = 0;
+				ValueChanged.Raise (this, new ValueChangeEventArgs ("MaximumScroll", maxScroll));
+			}
+		}
+		void onChildListCleared(object sender, EventArgs e){
+			ScrollY = 0;
+			ScrollX = 0;
 		}
 		public override T SetChild<T> (T _child)
 		{			
 			GraphicObject c = child as GraphicObject;
-			if (c != null)
+			Group g = child as Group;
+			if (c != null) {
 				c.LayoutChanged -= OnChildLayoutChanges;
+				if (g != null)
+					g.ChildrenCleared -= onChildListCleared;
+			}
 			c = _child as GraphicObject;
-			if (c != null)
+			g = _child as Group;
+			if (c != null) {
 				c.LayoutChanged += OnChildLayoutChanges;
+				if (g != null)
+					g.ChildrenCleared += onChildListCleared;				
+			}
 			return base.SetChild (_child);
 		}
 		#endregion
-- 
2.47.3