Experiment with using a flowbox layout to handle the toolbox widget o…

…verflowing

This produces multiple columns instead of introducing a scrollbar that can interfere with clicks.

Pinta.Core/Managers/ChromeManager.cs

@@ -47,7 +47,7 @@ public sealed class ChromeManager
 
 	public Box MainToolBar { get; private set; } = null!;
 	public Box ToolToolBar { get; private set; } = null!;
-	public Box ToolBox { get; private set; } = null!;
+	public Widget ToolBox { get; private set; } = null!;
 	public Box StatusBar { get; private set; } = null!;
 
 	public IProgressDialog ProgressDialog => progress_dialog;
@@ -108,7 +108,7 @@ public void InitializeStatusBar (Box statusbar)
 		StatusBar = statusbar;
 	}
 
-	public void InitializeToolBox (Box toolbox)
+	public void InitializeToolBox (Widget toolbox)
 	{
 		ToolBox = toolbox;
 	}

Pinta.Gui.Widgets/Widgets/ToolBoxWidget.cs

@@ -4,7 +4,7 @@
 
 namespace Pinta.Gui.Widgets;
 
-public sealed class ToolBoxWidget : Box
+public sealed class ToolBoxWidget : FlowBox
 {
 	public ToolBoxWidget ()
 	{
@@ -15,21 +15,19 @@ public ToolBoxWidget ()
 		PintaCore.Tools.ToolRemoved += HandleToolRemoved;
 
 		SetOrientation (Orientation.Vertical);
-		Spacing = 0;
+		ColumnSpacing = 0;
+		RowSpacing = 0;
+		Homogeneous = true;
+		MinChildrenPerLine = 6;
+		MaxChildrenPerLine = 1024; // If there is enough vertical space, only use one column
+		Vexpand = false;
+		Valign = Align.Start;
 	}
 
 	public void AddItem (ToolBoxButton item)
 	{
 		var index = PintaCore.Tools.ToList ().IndexOf (item.Tool);
-
-		Widget? prev_widget = null;
-		if (index > 0) {
-			prev_widget = GetFirstChild ();
-			for (int i = 1; i < index; ++i)
-				prev_widget = prev_widget!.GetNextSibling ();
-		}
-
-		InsertChildAfter (item.Tool.ToolItem, prev_widget);
+		Insert (item.Tool.ToolItem, index);
 	}
 
 	public void RemoveItem (ToolBoxButton item)

Pinta/MainWindow.cs

@@ -438,7 +438,7 @@ private void CreateDockAndPads (Box container)
 		var toolbox_scroll = new ScrolledWindow () {
 			Child = toolbox,
 			HscrollbarPolicy = PolicyType.Never,
-			VscrollbarPolicy = PolicyType.Automatic,
+			VscrollbarPolicy = PolicyType.Never,
 			HasFrame = false,
 			OverlayScrolling = true,
 			WindowPlacement = CornerType.BottomRight