[Debugger] Simplify PinnedWatchView, allow scrolling children via popover

Currently, the editor intercepts scrolling events that an adornment
such as the PinnedWatchView might want to receive. This prevents such an
adornment from being properly scrollable.

Looking at how pinned watches work on Windows, however, the watch itself
cannot be expanded. Rather, the user can click an expand button to see
the child items in a popup. Inspired by this, I have removed scrolling
and expansion from the PinnedWatchView, and made it so hovering a watch
shows the same popover tooltip (which _is_ scrollable, as it's a child
window) that one sees when hovering a value in the editor.

A few notes:

* Changed the data source to not add child nodes at all when
  `AllowExpanding` is not set on the tree view. This ensures there will
  be no disclosure triangle.
* Pinned watches whose values do not have children will not get a
  tooltip.
* When hovering a pinned watch, the root node will always be expanded.
* The only way to dismiss the watch's popover tooltip is to press ESC
  or click elsewhere. This actually feels pretty good.
* Child expansion state in the tooltip is preserved as long as the watch
  remains pinned.

Fixes: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/999603

Author: sandyarmstrong

main/src/addins/MonoDevelop.Debugger/MonoDevelop.Debugger.VSTextView/PinnedWatches/PinnedWatchView.cs

@@ -32,39 +32,43 @@
 
 namespace MonoDevelop.Debugger.VSTextView.PinnedWatches
 {
-	sealed class PinnedWatchView : NSScrollView
+	sealed class PinnedWatchView : NSView
 	{
+		readonly PinnedWatch watch;
+		readonly StackFrame frame;
 		readonly ObjectValueTreeViewController controller;
 		readonly NSLayoutConstraint heightConstraint;
 		readonly NSLayoutConstraint widthConstraint;
 		readonly MacObjectValueTreeView treeView;
+		MacDebuggerTooltipWindow popover;
 		NSLayoutConstraint superHeightConstraint;
 		NSLayoutConstraint superWidthConstraint;
 		ObjectValue objectValue;
 		bool disposed;
 
 		public PinnedWatchView (PinnedWatch watch, StackFrame frame)
 		{
-			HasVerticalScroller = true;
-			AutohidesScrollers = true;
+			this.watch = watch ?? throw new ArgumentNullException (nameof (watch));
+			this.frame = frame;
 
 			controller = new ObjectValueTreeViewController ();
 			controller.SetStackFrame (frame);
 			controller.AllowEditing = true;
+			controller.AllowExpanding = false;
 
 			treeView = controller.GetMacControl (headersVisible: false, compactView: true, allowPinning: true);
 
 			controller.PinnedWatch = watch;
 
 			if (watch.Value != null)
-				controller.AddValue (watch.Value);
+				controller.AddValue (objectValue = watch.Value);
 
 			var rect = treeView.Frame;
 
 			if (rect.Height < 1)
 				treeView.Frame = new CoreGraphics.CGRect (rect.X, rect.Y, rect.Width, 19);
 
-			DocumentView = treeView;
+			AddSubview (treeView);
 			Frame = treeView.Frame;
 
 			heightConstraint = HeightAnchor.ConstraintEqualToConstant (treeView.Frame.Height);
@@ -76,6 +80,27 @@ public PinnedWatchView (PinnedWatch watch, StackFrame frame)
 			DebuggingService.ResumedEvent += OnDebuggerResumed;
 			DebuggingService.PausedEvent += OnDebuggerPaused;
 			treeView.Resized += OnTreeViewResized;
+
+			AddTrackingArea (new NSTrackingArea (
+				default,
+				NSTrackingAreaOptions.ActiveInActiveApp |
+				NSTrackingAreaOptions.InVisibleRect |
+				NSTrackingAreaOptions.MouseEnteredAndExited,
+				this,
+				null));
+		}
+
+		public override void MouseEntered (NSEvent theEvent)
+		{
+			if (popover != null && popover.Shown)
+				return;
+
+			if (objectValue != null && objectValue.HasChildren) {
+				if (popover == null)
+					popover = new MacDebuggerTooltipWindow (watch.Location, frame, objectValue, watch);
+				popover.Show (treeView.Frame, this, NSRectEdge.MaxXEdge);
+				popover.Expand ();
+			}
 		}
 
 		public void SetObjectValue (ObjectValue value)
@@ -136,41 +161,16 @@ void OnTreeViewResized (object sender, EventArgs e)
 
 			superHeightConstraint.Constant = height;
 			superWidthConstraint.Constant = width;
-
-#if REPARENT_SO_SCROLLING_WORKS
-			// Find our parent CocoaEditorGridView
-			var gridView = textView.Superview;
-			while (gridView != null && gridView.GetType ().Name != CocoaEditorGridView)
-				gridView = gridView.Superview;
-
-			if (gridView == null)
-				return;
-
-			// Find the CocoaTextViewScrollView
-			NSView textViewScrollView = null;
-			foreach (var child in gridView.Subviews) {
-				if (child.GetType ().Name == CocoaTextViewScrollView) {
-					textViewScrollView = child;
-					break;
-				}
-			}
-
-			materialView.RemoveFromSuperview ();
-
-			gridView.AddSubview (materialView, NSWindowOrderingMode.Above, textViewScrollView);
-#endif
 		}
 
 		void OnDebuggerResumed (object sender, EventArgs e)
 		{
 			controller.ChangeCheckpoint ();
-			controller.AllowExpanding = false;
 			controller.AllowEditing = false;
 		}
 
 		void OnDebuggerPaused (object sender, EventArgs e)
 		{
-			controller.AllowExpanding = true;
 			controller.AllowEditing = true;
 		}
 

main/src/addins/MonoDevelop.Debugger/MonoDevelop.Debugger.VSTextView/QuickInfo/MacDebuggerTooltipWindow.cs

@@ -78,6 +78,11 @@ public MacDebuggerTooltipWindow (PinnedWatchLocation location, StackFrame frame,
 			treeView.Resized += OnTreeViewResized;
 		}
 
+		public void Expand ()
+		{
+			treeView.ExpandItem (treeView.ItemAtRow (0), false);
+		}
+
 		public DebuggerSession GetDebuggerSession ()
 		{
 			return controller.GetStackFrame ()?.DebuggerSession;

main/src/addins/MonoDevelop.Debugger/MonoDevelop.Debugger/ObjectValue/Mac/MacObjectValueTreeViewDataSource.cs

@@ -75,11 +75,13 @@ void Add (MacObjectValueNode parent, ObjectValueNode node)
 
 			parent.Children.Add (value);
 
-			foreach (var child in node.Children)
-				Add (value, child);
+			if (treeView.AllowExpanding) {
+				foreach (var child in node.Children)
+					Add (value, child);
 
-			if (node.HasChildren && !node.ChildrenLoaded)
-				Add (value, new LoadingObjectValueNode (node));
+				if (node.HasChildren && !node.ChildrenLoaded)
+					Add (value, new LoadingObjectValueNode (node));
+			}
 		}
 
 		void Insert (MacObjectValueNode parent, int index, ObjectValueNode node)
@@ -89,11 +91,13 @@ void Insert (MacObjectValueNode parent, int index, ObjectValueNode node)
 
 			parent.Children.Insert (index, value);
 
-			foreach (var child in node.Children)
-				Add (value, child);
+			if (treeView.AllowExpanding) {
+				foreach (var child in node.Children)
+					Add (value, child);
 
-			if (node.HasChildren && !node.ChildrenLoaded)
-				Add (value, new LoadingObjectValueNode (node));
+				if (node.HasChildren && !node.ChildrenLoaded)
+					Add (value, new LoadingObjectValueNode (node));
+			}
 		}
 
 		void Remove (MacObjectValueNode node, List<MacObjectValueNode> removed)