diff --git a/src/BizHawk.Client.Common/Api/Classes/EmuClientApi.cs b/src/BizHawk.Client.Common/Api/Classes/EmuClientApi.cs
index 36c8715e6a..f0f55349b9 100644
--- a/src/BizHawk.Client.Common/Api/Classes/EmuClientApi.cs
+++ b/src/BizHawk.Client.Common/Api/Classes/EmuClientApi.cs
@@ -11,7 +11,7 @@ namespace BizHawk.Client.Common
 	{
 		private readonly Config _config;
 
-		private readonly IWindowCoordsTransformer _displayManager;
+		private readonly DisplayManagerBase _displayManager;
 
 		private readonly IMainFormForApi _mainForm;
 
@@ -35,7 +35,7 @@ namespace BizHawk.Client.Common
 
 		public event StateSavedEventHandler StateSaved;
 
-		public EmuClientApi(Action<string> logCallback, IMainFormForApi mainForm, IWindowCoordsTransformer displayManager, Config config, IEmulator emulator, IGameInfo game)
+		public EmuClientApi(Action<string> logCallback, IMainFormForApi mainForm, DisplayManagerBase displayManager, Config config, IEmulator emulator, IGameInfo game)
 		{
 			_config = config;
 			_displayManager = displayManager;
diff --git a/src/BizHawk.Client.Common/Api/Classes/GuiApi.cs b/src/BizHawk.Client.Common/Api/Classes/GuiApi.cs
index 8cdac8fa3d..9a4b0d0478 100644
--- a/src/BizHawk.Client.Common/Api/Classes/GuiApi.cs
+++ b/src/BizHawk.Client.Common/Api/Classes/GuiApi.cs
@@ -17,7 +17,7 @@ namespace BizHawk.Client.Common
 
 		private readonly Action<string> LogCallback;
 
-		private readonly IDisplayManagerForApi _displayManager;
+		private readonly DisplayManagerBase _displayManager;
 
 		private readonly Dictionary<string, Image> _imageCache = new Dictionary<string, Image>();
 
@@ -51,7 +51,7 @@ namespace BizHawk.Client.Common
 
 		public bool HasGUISurface => _GUISurface != null;
 
-		public GuiApi(Action<string> logCallback, IDisplayManagerForApi displayManager)
+		public GuiApi(Action<string> logCallback, DisplayManagerBase displayManager)
 		{
 			LogCallback = logCallback;
 			_displayManager = displayManager;
diff --git a/src/BizHawk.Client.Common/Api/Classes/InputApi.cs b/src/BizHawk.Client.Common/Api/Classes/InputApi.cs
index 3839ea348f..e54c147a92 100644
--- a/src/BizHawk.Client.Common/Api/Classes/InputApi.cs
+++ b/src/BizHawk.Client.Common/Api/Classes/InputApi.cs
@@ -5,11 +5,11 @@ namespace BizHawk.Client.Common
 {
 	public sealed class InputApi : IInputApi
 	{
-		private readonly IWindowCoordsTransformer _displayManager;
+		private readonly DisplayManagerBase _displayManager;
 
 		private readonly InputManager _inputManager;
 
-		public InputApi(IWindowCoordsTransformer displayManager, InputManager inputManager)
+		public InputApi(DisplayManagerBase displayManager, InputManager inputManager)
 		{
 			_displayManager = displayManager;
 			_inputManager = inputManager;
diff --git a/src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs b/src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs
index 913c86f40c..fd64449542 100644
--- a/src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs
+++ b/src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs
@@ -25,7 +25,7 @@ namespace BizHawk.Client.Common
 	/// Its job is to receive OSD and emulator outputs, and produce one single buffer (BitmapBuffer? Texture2d?) for display by the PresentationPanel.
 	/// Details TBD
 	/// </summary>
-	public class DisplayManagerBase : IDisplayManagerForApi, IWindowCoordsTransformer, IDisposable
+	public class DisplayManagerBase : IDisposable
 	{
 		private static DisplaySurface CreateDisplaySurface(int w, int h) => new(w, h);
 
diff --git a/src/BizHawk.Client.Common/DisplayManager/IDisplayManagerForApi.cs b/src/BizHawk.Client.Common/DisplayManager/IDisplayManagerForApi.cs
deleted file mode 100644
index fb21ab02db..0000000000
--- a/src/BizHawk.Client.Common/DisplayManager/IDisplayManagerForApi.cs
+++ /dev/null
@@ -1,20 +0,0 @@
-using System;
-using System.Drawing.Text;
-
-namespace BizHawk.Client.Common
-{
-	public interface IDisplayManagerForApi
-	{
-		PrivateFontCollection CustomFonts { get; }
-
-		OSDManager OSD { get; }
-
-		/// <summary>locks the surface with ID <paramref name="surfaceID"/></summary>
-		/// <exception cref="InvalidOperationException">already locked, or unknown surface</exception>
-		IDisplaySurface LockApiHawkSurface(DisplaySurfaceID surfaceID, bool clear = true);
-
-		/// <summary>unlocks the given <paramref name="surface"/>, which must be a locked surface produced by <see cref="LockApiHawkSurface"/></summary>
-		/// <exception cref="InvalidOperationException">already unlocked</exception>
-		void UnlockApiHawkSurface(IDisplaySurface surface);
-	}
-}
diff --git a/src/BizHawk.Client.Common/DisplayManager/IWindowCoordsTransformer.cs b/src/BizHawk.Client.Common/DisplayManager/IWindowCoordsTransformer.cs
deleted file mode 100644
index 8a05772c12..0000000000
--- a/src/BizHawk.Client.Common/DisplayManager/IWindowCoordsTransformer.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System.Drawing;
-
-namespace BizHawk.Client.Common
-{
-	public interface IWindowCoordsTransformer
-	{
-		(int Left, int Top, int Right, int Bottom) ClientExtraPadding { get; set; }
-
-		(int Left, int Top, int Right, int Bottom) GameExtraPadding { get; set; }
-
-		Size GetPanelNativeSize();
-
-		Point TransformPoint(Point p);
-
-		Point UntransformPoint(Point p);
-	}
-}
diff --git a/src/BizHawk.Client.EmuHawk/Api/ApiManager.cs b/src/BizHawk.Client.EmuHawk/Api/ApiManager.cs
index 703f1b15a4..c0c0733431 100644
--- a/src/BizHawk.Client.EmuHawk/Api/ApiManager.cs
+++ b/src/BizHawk.Client.EmuHawk/Api/ApiManager.cs
@@ -36,7 +36,7 @@ namespace BizHawk.Client.EmuHawk
 			IEmulatorServiceProvider serviceProvider,
 			Action<string> logCallback,
 			IMainFormForApi mainForm,
-			IDisplayManagerForApi displayManager,
+			DisplayManagerBase displayManager,
 			InputManager inputManager,
 			IMovieSession movieSession,
 			ToolManager toolManager,
@@ -48,8 +48,7 @@ namespace BizHawk.Client.EmuHawk
 			{
 				[typeof(Action<string>)] = logCallback,
 				[typeof(IMainFormForApi)] = mainForm,
-				[typeof(IDisplayManagerForApi)] = displayManager,
-				[typeof(IWindowCoordsTransformer)] = displayManager,
+				[typeof(DisplayManagerBase)] = displayManager,
 				[typeof(InputManager)] = inputManager,
 				[typeof(IMovieSession)] = movieSession,
 				[typeof(ToolManager)] = toolManager,
@@ -71,7 +70,7 @@ namespace BizHawk.Client.EmuHawk
 		public static IExternalApiProvider Restart(
 			IEmulatorServiceProvider serviceProvider,
 			IMainFormForApi mainForm,
-			IDisplayManagerForApi displayManager,
+			DisplayManagerBase displayManager,
 			InputManager inputManager,
 			IMovieSession movieSession,
 			ToolManager toolManager,
@@ -88,7 +87,7 @@ namespace BizHawk.Client.EmuHawk
 			IEmulatorServiceProvider serviceProvider,
 			Action<string> logCallback,
 			IMainFormForApi mainForm,
-			IDisplayManagerForApi displayManager,
+			DisplayManagerBase displayManager,
 			InputManager inputManager,
 			IMovieSession movieSession,
 			ToolManager toolManager,
diff --git a/src/BizHawk.Client.EmuHawk/tools/Lua/Win32LuaLibraries.cs b/src/BizHawk.Client.EmuHawk/tools/Lua/Win32LuaLibraries.cs
index 4a6555fb40..26d576d913 100644
--- a/src/BizHawk.Client.EmuHawk/tools/Lua/Win32LuaLibraries.cs
+++ b/src/BizHawk.Client.EmuHawk/tools/Lua/Win32LuaLibraries.cs
@@ -20,7 +20,7 @@ namespace BizHawk.Client.EmuHawk
 			LuaFunctionList registeredFuncList,
 			IEmulatorServiceProvider serviceProvider,
 			MainForm mainForm,
-			IDisplayManagerForApi displayManager,
+			DisplayManagerBase displayManager,
 			InputManager inputManager,
 			Config config,
 			IEmulator emulator,
@@ -110,7 +110,7 @@ namespace BizHawk.Client.EmuHawk
 
 		private ApiContainer _apiContainer;
 
-		private readonly IDisplayManagerForApi _displayManager;
+		private readonly DisplayManagerBase _displayManager;
 
 		private GuiApi GuiAPI => (GuiApi) _apiContainer.Gui;