fix ExListView group header collapse-expand button

GitUI/GitUI.csproj

@@ -370,6 +370,7 @@
     <Compile Include="SpellChecker\WordAtCursorExtractor.cs" />
     <Compile Include="TaskbarProgress.cs" />
     <Compile Include="UserControls\RevisionGrid\CellStyle.cs" />
+    <Compile Include="UserControls\ListViewGroupHitInfo.cs" />
     <Compile Include="UserControls\RevisionGrid\Graph\JunctionColorProvider.cs" />
     <Compile Include="UserControls\RevisionGrid\Graph\JunctionStyler.cs" />
     <Compile Include="UserControls\RevisionGrid\Columns\MultilineIndicator.cs" />

GitUI/UserControls/ExListView.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Drawing;
 using System.Reflection;
 using System.Runtime.InteropServices;
 using System.Windows.Forms;
@@ -60,9 +61,14 @@ internal class ExListView : NativeListView
         private static readonly PropertyInfo ListViewGroupIdProperty;
 
         /// <summary>
-        /// Occurs when the user clicks a <see cref="ListViewGroup"/> within the list view control.
+        /// Occurs when the user presses mouse button in a <see cref="ListViewGroup"/> within the list view control.
         /// </summary>
-        public event EventHandler<ListViewGroupMouseEventArgs> GroupMouseClick;
+        public event EventHandler<ListViewGroupMouseEventArgs> GroupMouseDown;
+
+        /// <summary>
+        /// Occurs when the user releases mouse button in a <see cref="ListViewGroup"/> within the list view control.
+        /// </summary>
+        public event EventHandler<ListViewGroupMouseEventArgs> GroupMouseUp;
 
         static ExListView()
         {
@@ -103,6 +109,9 @@ private static class NativeMethods
             public const int LVM_SETGROUPINFO = LVM_FIRST + 147;
             public const int LVM_SUBITEMHITTEST = LVM_FIRST + 57;
 
+            public const int NM_FIRST = 0;
+            public const int NM_CUSTOMDRAW = NM_FIRST - 12;
+
             #endregion
 
             [StructLayout(LayoutKind.Sequential)]
@@ -219,88 +228,95 @@ public struct LVGROUP
 
         protected override void WndProc(ref Message m)
         {
+            var message = m;
+            var groupHitInfo = new Lazy<ListViewGroupHitInfo>(() => GetGroupHitInfo(message));
+
             switch (m.Msg)
             {
+                case NativeMethods.WM_LBUTTONUP when groupHitInfo.Value?.IsCollapseButton == true:
+                    DefWndProc(ref m); // collapse / expand by clicking button in group header
+                    break;
+
                 case NativeMethods.WM_PAINT:
                     _isInWmPaintMsg = true;
                     base.WndProc(ref m);
                     _isInWmPaintMsg = false;
                     break;
-                case NativeMethods.WM_REFLECT_NOTIFY:
-                    var nmhdr = (NativeMethods.NMHDR)m.GetLParam(typeof(NativeMethods.NMHDR));
-                    if (nmhdr.code == -12)
-                    {
-                        // NM_CUSTOMDRAW
-                        if (_isInWmPaintMsg)
-                        {
-                            base.WndProc(ref m);
-                        }
-                    }
-                    else
-                    {
-                        base.WndProc(ref m);
-                    }
 
+                case NativeMethods.WM_REFLECT_NOTIFY when IsCustomDraw(m) && !_isInWmPaintMsg:
+                case NativeMethods.WM_RBUTTONUP when IsGroupMouseEventHandled(groupHitInfo.Value, MouseButtons.Right, isDown: false):
+                case NativeMethods.WM_RBUTTONDOWN when IsGroupMouseEventHandled(groupHitInfo.Value, MouseButtons.Right, isDown: true):
+                case NativeMethods.WM_LBUTTONUP when IsGroupMouseEventHandled(groupHitInfo.Value, MouseButtons.Left, isDown: false):
+                case NativeMethods.WM_LBUTTONDOWN when IsGroupMouseEventHandled(groupHitInfo.Value, MouseButtons.Left, isDown: true):
                     break;
-                case NativeMethods.WM_LBUTTONUP:
-                case NativeMethods.WM_LBUTTONDOWN:
-                    {
-                        if (IsListViewGroupClickHandled((uint)m.LParam, MouseButtons.Left))
-                        {
-                            return;
-                        }
-
-                        base.WndProc(ref m);
-                        break;
-                    }
-
-                case NativeMethods.WM_RBUTTONUP:
-                case NativeMethods.WM_RBUTTONDOWN:
-                    {
-                        if (IsListViewGroupClickHandled((uint)m.LParam, MouseButtons.Right))
-                        {
-                            return;
-                        }
-
-                        base.WndProc(ref m);
-                        break;
-                    }
 
                 default:
                     base.WndProc(ref m);
                     break;
             }
 
-            bool IsListViewGroupClickHandled(uint lparam, MouseButtons button)
+            bool IsGroupMouseEventHandled(ListViewGroupHitInfo hitInfo, MouseButtons button, bool isDown)
             {
-                var info = new NativeMethods.LVHITTESTINFO
-                {
-                    pt = NativeMethods.LParamToPOINT(lparam)
-                };
-
-                var handleRef = new HandleRef(this, Handle);
-                if (NativeMethods.SendMessage(handleRef, NativeMethods.LVM_SUBITEMHITTEST, (IntPtr)(-1), ref info) == new IntPtr(-1))
+                if (hitInfo == null)
                 {
                     return false;
                 }
 
-                if ((info.flags & NativeMethods.LVHITTESTFLAGS.LVHT_EX_GROUP_HEADER) == 0)
+                var eventArgs = new ListViewGroupMouseEventArgs(button, hitInfo, 1, 0);
+                if (isDown)
                 {
-                    return false;
+                    GroupMouseDown?.Invoke(this, eventArgs);
                 }
-
-                foreach (ListViewGroup group in Groups)
+                else
                 {
-                    var groupId = GetGroupId(group);
-                    if (info.iItem == groupId)
-                    {
-                        GroupMouseClick?.Invoke(this, new ListViewGroupMouseEventArgs(button, group, 1, info.pt.X, info.pt.Y, 0));
-                        return true;
-                    }
+                    GroupMouseUp?.Invoke(this, eventArgs);
                 }
 
-                return false;
+                return eventArgs.Handled;
+            }
+
+            bool IsCustomDraw(Message msg)
+            {
+                var nmhdr = (NativeMethods.NMHDR)msg.GetLParam(typeof(NativeMethods.NMHDR));
+                return nmhdr.code == NativeMethods.NM_CUSTOMDRAW;
+            }
+        }
+
+        private ListViewGroupHitInfo GetGroupHitInfo(Message msg)
+        {
+            var point = NativeMethods.LParamToPOINT((uint)msg.LParam);
+            return GetGroupHitInfo(point);
+        }
+
+        private ListViewGroupHitInfo GetGroupHitInfo(NativeMethods.POINT location)
+        {
+            var info = new NativeMethods.LVHITTESTINFO
+            {
+                pt = location
+            };
+
+            var handleRef = new HandleRef(this, Handle);
+            if (NativeMethods.SendMessage(handleRef, NativeMethods.LVM_SUBITEMHITTEST, (IntPtr)(-1), ref info) == new IntPtr(-1))
+            {
+                return null;
             }
+
+            if ((info.flags & NativeMethods.LVHITTESTFLAGS.LVHT_EX_GROUP_HEADER) == 0)
+            {
+                return null;
+            }
+
+            foreach (ListViewGroup group in Groups)
+            {
+                var groupId = GetGroupId(group);
+                if (info.iItem == groupId)
+                {
+                    bool isCollapseButton = (info.flags & NativeMethods.LVHITTESTFLAGS.LVHT_EX_GROUP_COLLAPSE) > 0;
+                    return new ListViewGroupHitInfo(group, isCollapseButton, new Point(location.X, location.Y));
+                }
+            }
+
+            return null;
         }
 
         private static int GetGroupId(ListViewGroup listViewGroup)

GitUI/UserControls/FileStatusList.cs

@@ -506,6 +506,15 @@ private void FileStatusListView_MouseMove(object sender, MouseEventArgs e)
             }
         }
 
+        private void FileStatusListView_GroupMouseDown(object sender, ListViewGroupMouseEventArgs e)
+        {
+            if (e.Button == MouseButtons.Left)
+            {
+                // prevent selecting all sub-items when left-clicking group
+                e.Handled = true;
+            }
+        }
+
         public int UnfilteredItemsCount => GitItemStatusesWithParents?.Sum(tuple => tuple.statuses.Count) ?? 0;
 
         public int AllItemsCount => FileStatusListView.Items.Count;

GitUI/UserControls/ListViewGroupHitInfo.cs

@@ -0,0 +1,19 @@
+using System.Drawing;
+using System.Windows.Forms;
+
+namespace GitUI.UserControls
+{
+    public class ListViewGroupHitInfo
+    {
+        public ListViewGroupHitInfo(ListViewGroup @group, bool isCollapseButton, Point location)
+        {
+            Group = @group;
+            IsCollapseButton = isCollapseButton;
+            Location = location;
+        }
+
+        public ListViewGroup Group { get; }
+        public bool IsCollapseButton { get; }
+        public Point Location { get; }
+    }
+}

GitUI/UserControls/ListViewGroupMouseEventArgs.cs

@@ -5,12 +5,13 @@ namespace GitUI.UserControls
     /// <inheritdoc />
     internal class ListViewGroupMouseEventArgs : MouseEventArgs
     {
-        public ListViewGroupMouseEventArgs(MouseButtons button, ListViewGroup group, int clicks, int x, int y, int delta)
-            : base(button, clicks, x, y, delta)
+        public ListViewGroupMouseEventArgs(MouseButtons button, ListViewGroupHitInfo groupHitInfo, int clicks, int delta)
+            : base(button, clicks, groupHitInfo.Location.X, groupHitInfo.Location.Y, delta)
         {
-            Group = group;
+            GroupInfo = groupHitInfo;
         }
 
-        public ListViewGroup Group { get; }
+        public ListViewGroupHitInfo GroupInfo { get; }
+        public bool Handled { get; set; }
     }
 }