Use custom gtk theme when compiling and running on widows

EstusShots.Gtk/EstusShots.Gtk.csproj

@@ -14,6 +14,10 @@
         <EmbeddedResource Include="Icons\icon.png">
             <LogicalName>%(Filename)%(Extension)</LogicalName>
         </EmbeddedResource>
+
+        <Content Include="Theme\**\*" Condition="$(NETCoreSdkRuntimeIdentifier) == 'win-x64'">
+            <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+        </Content>
     </ItemGroup>
 
     <ItemGroup>
@@ -27,6 +31,7 @@
 
     <ItemGroup>
       <Folder Include="Dialogs\Glade" />
+      <Folder Include="Theme" />
     </ItemGroup>
 
 </Project>

EstusShots.Gtk/Program.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.InteropServices;
 using Gtk;
 
 namespace EstusShots.Gtk
@@ -10,6 +11,17 @@ namespace EstusShots.Gtk
         {
             Application.Init();
 
+            // Load a custom theme only when running on windows
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                var provider = new CssProvider();
+                provider.LoadFromPath("Theme/gtk-3.20/gtk.css");
+                StyleContext.AddProviderForScreen(Gdk.Screen.Default, provider, 800);
+                
+                // TODO ????
+                //IconTheme.Default.PrependSearchPath("Theme/icons/48x48");
+            }
+            
             var app = new Application("EstusShots.Gtk", GLib.ApplicationFlags.None);
             app.Register(GLib.Cancellable.Current);