Disable "borderless window fullscreen" support on Linux for now. (#1480)

* Disable "borderless window fullscreen" support on Linux for now.
This has never quite worked properly; screen mode setting behaves
inconsistently between X11 and Wayland sessions.

* Remove inadvertently-added "using"

Author: lemming104

Client/Window.cs

@@ -284,6 +284,13 @@ public void UpdateWindow()
                     GLFW.SetWindowMonitor(WindowPtr, monitor, 0, 0, modePtr->Width, modePtr->Height, modePtr->RefreshRate);
                     break;
                 case RenderWindowState.BorderlessFullscreenWindow:
+                    if (OperatingSystem.IsLinux())
+                    {
+                        // Borderless fullscreen mode changes on linux are _really_ inconsistent, so let's just not do that for now.
+                        GLFW.SetWindowMonitor(WindowPtr, monitor, 0, 0, modePtr->Width, modePtr->Height, modePtr->RefreshRate);
+                        break;
+                    }
+
                     // Hide border before going fullscreen, otherwise taskbar gets stuck on Windows
                     WindowBorder = WindowBorder.Hidden;
                     WindowState = WindowState.Normal;
@@ -311,16 +318,6 @@ public void UpdateWindow()
                         GLFW.RestoreWindow(WindowPtr);
                     }
 
-                    if (m_isLinuxX11 && oldWindowState == RenderWindowState.BorderlessFullscreenWindow)
-                    {
-                        // Note:  There seems to be a weird bug here where if the application is started in borderless, 
-                        // and then the user goes to Windowed _without ever moving their mouse_, the mouse cursor gets "stuck"
-                        // in a narrow range and cannot be moved.
-
-                        // Need to quickly bounce through full-screen for...reasons?
-                        GLFW.SetWindowMonitor(WindowPtr, monitor, 0, 0, modePtr->Width, modePtr->Height, modePtr->RefreshRate);
-                    }
-
                     // Note: Wayland (at least on Gnome, Ubuntu 24.04) seems to ignore window decor settings.
                     WindowBorder = m_config.Window.Border;
                     GLFW.SetWindowMonitor(WindowPtr, null, windowX, windowY, (int)(windowDimension.Width / m_clientScaling.X), (int)(windowDimension.Height / m_clientScaling.Y), GLFW.DontCare);

Core/Util/Configs/Components/ConfigWindow.cs

@@ -78,7 +78,7 @@ public class ConfigWindow: ConfigElement<ConfigWindow>
     [OptionMenu(OptionSectionType.Video, "Render Mode")]
     public readonly ConfigValue<ConfigRenderMode> RenderMode = new(ConfigRenderMode.TrueColorFast);
 
-    [ConfigInfo("Display fullscreen or windowed.")]
+    [ConfigInfo("Display fullscreen or windowed.  Borderless Fullscreen is treated as Fullscreen on Linux.")]
     [OptionMenu(OptionSectionType.Video, "Fullscreen/Window", allowReset: false, spacer: true)]
     public readonly ConfigValue<RenderWindowState> State = new(RenderWindowState.Fullscreen, OnlyValidEnums<RenderWindowState>());