Restores the palette picker in decals (#7635)

Content.Client/Decals/UI/DecalPlacerWindow.xaml

@@ -11,7 +11,10 @@
             </GridContainer>
         </ScrollContainer>
 
-        <ColorSelectorSliders Name="ColorPicker" IsAlphaVisible="True" />
+        <BoxContainer Orientation="Vertical">
+            <ColorSelectorSliders Name="ColorPicker" IsAlphaVisible="True" />
+            <Button Name="PickerOpen" Text="{Loc 'decal-placer-window-palette'}" />
+        </BoxContainer>
         <CheckBox Name="EnableColor" Text="{Loc 'decal-placer-window-use-color'}" />
         <CheckBox Name="EnableSnap" Text="{Loc 'decal-placer-window-enable-snap'}" />
         <CheckBox Name="EnableCleanable" Text="{Loc 'decal-placer-window-enable-cleanable'}" />

Content.Client/Decals/UI/DecalPlacerWindow.xaml.cs

@@ -1,4 +1,5 @@
-using Content.Client.Stylesheets;
+using System.Linq;
+using Content.Client.Stylesheets;
 using Content.Shared.Decals;
 using Robust.Client.AutoGenerated;
 using Robust.Client.Graphics;
@@ -19,6 +20,8 @@ public sealed partial class DecalPlacerWindow : DefaultWindow
 
     public FloatSpinBox RotationSpinBox;
 
+    private PaletteColorPicker? _picker;
+
     private Dictionary<string, Texture>? _decals;
     private string? _selected;
     private Color _color = Color.White;
@@ -44,12 +47,34 @@ public sealed partial class DecalPlacerWindow : DefaultWindow
         SpinBoxContainer.AddChild(RotationSpinBox);
 
         Search.OnTextChanged += _ => RefreshList();
-        ColorPicker.OnColorChanged += color =>
+        ColorPicker.OnColorChanged += OnColorPicked;
+
+        PickerOpen.OnPressed += _ =>
         {
-            _color = color;
-            UpdateDecalPlacementInfo();
-            RefreshList();
+            if (_picker is null)
+            {
+                _picker = new PaletteColorPicker();
+                _picker.OpenToLeft();
+                _picker.PaletteList.OnItemSelected += args =>
+                {
+                    var color = (args.ItemList.GetSelected().First().Metadata as Color?)!.Value;
+                    ColorPicker.Color = color;
+                    OnColorPicked(color);
+                };
+            }
+            else
+            {
+                if (_picker.IsOpen)
+                {
+                    _picker.Close();
+                }
+                else
+                {
+                    _picker.Open();
+                }
+            }
         };
+
         RotationSpinBox.OnValueChanged += args =>
         {
             _rotation = args.Value;
@@ -77,6 +102,13 @@ public sealed partial class DecalPlacerWindow : DefaultWindow
         Populate();
     }
 
+    private void OnColorPicked(Color color)
+    {
+        _color = color;
+        UpdateDecalPlacementInfo();
+        RefreshList();
+    }
+
     private void UpdateDecalPlacementInfo()
     {
         if (_selected is null)