Disable X11 on Wayland unless explicitly activated.

private/raid/application.cpp

@@ -426,9 +426,9 @@ void Application::cleanup()
 bool Application::initSDL()
 {
 #if MIJIN_TARGET_OS == MIJIN_OS_LINUX
-    // prefer x11 over wayland, as ImGui viewports don't work with wayland
-    // TODO: this still doesn't work all the time, maybe there will be an update to ImGui in the future?
+    if (mConfig.flags.x11OnWayland) {
         SDL_SetHint(SDL_HINT_VIDEO_DRIVER, "x11,wayland");
+    }
 #endif
     if (!SDL_Init(SDL_INIT_VIDEO))
     {

public/raid/raid.hpp

@@ -51,6 +51,21 @@ struct FontConfig
     FontFlags flags;
 };
 
+struct ApplicationFlags : mijin::BitFlags<ApplicationFlags>
+{
+    /**
+     * (Linux only) prefer X11 even when on Wayland. Required for multi-viewport support, but currently really buggy.
+     * \see https://github.com/ocornut/imgui/issues/8609
+     * \see https://github.com/ocornut/imgui/issues/8587
+     */
+    bool x11OnWayland : 1 = false;
+};
+
+struct ApplicationConfig
+{
+    ApplicationFlags flags = {};
+};
+
 class Application
 {
 private:
@@ -65,6 +80,7 @@ private:
     bool mRunning = true;
     ImGuiWindowFlags mMainWindowFlags = DEFAULT_MAIN_WINDOW_FLAGS;
     std::unordered_map<ImGuiStyleVar, std::variant<float, ImVec2>> mMainWindowStyles;
+    const ApplicationConfig mConfig;
 
     using GLbitfield = std::uint32_t;
     using GLint = std::int32_t;
@@ -91,8 +107,12 @@ private:
     glTexImage2D_fn_t glTexImage2D;
     glDeleteTextures_fn_t glDeleteTextures;
 public:
+    explicit Application(ApplicationConfig config = {}) noexcept : mConfig(config) {}
     virtual ~Application() = default;
 
+    [[nodiscard]]
+    const ApplicationConfig& getConfig() const noexcept { return mConfig; }
+
     [[nodiscard]]
     mijin::StackedFileSystemAdapter& getFS() { return mFS; }