6 files changed, 40 insertions, 11 deletions
diff --git a/platform/linuxbsd/x11/display_server_x11.cpp b/platform/linuxbsd/x11/display_server_x11.cpp
index d6eb101a68..4a52e26373 100644
--- a/platform/linuxbsd/x11/display_server_x11.cpp
+++ b/platform/linuxbsd/x11/display_server_x11.cpp
@@ -1735,7 +1735,7 @@ Vector<DisplayServer::WindowID> DisplayServerX11::get_window_list() const {
 	return ret;
 }
 
-DisplayServer::WindowID DisplayServerX11::create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect) {
+DisplayServer::WindowID DisplayServerX11::create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect, bool p_exclusive, WindowID p_transient_parent) {
 	_THREAD_SAFE_METHOD_
 
 	WindowID id = _create_window(p_mode, p_vsync_mode, p_flags, p_rect);
@@ -1749,6 +1749,11 @@ DisplayServer::WindowID DisplayServerX11::create_sub_window(WindowMode p_mode, V
 		rendering_device->screen_create(id);
 	}
 #endif
+
+	if (p_transient_parent != INVALID_WINDOW_ID) {
+		window_set_transient(id, p_transient_parent);
+	}
+
 	return id;
 }
 
diff --git a/platform/linuxbsd/x11/display_server_x11.h b/platform/linuxbsd/x11/display_server_x11.h
index 341ba5f079..0cbfbe51ef 100644
--- a/platform/linuxbsd/x11/display_server_x11.h
+++ b/platform/linuxbsd/x11/display_server_x11.h
@@ -438,7 +438,7 @@ public:
 
 	virtual Vector<DisplayServer::WindowID> get_window_list() const override;
 
-	virtual WindowID create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect = Rect2i()) override;
+	virtual WindowID create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect = Rect2i(), bool p_exclusive = false, WindowID p_transient_parent = INVALID_WINDOW_ID) override;
 	virtual void show_window(WindowID p_id) override;
 	virtual void delete_sub_window(WindowID p_id) override;
 
diff --git a/platform/macos/display_server_macos.h b/platform/macos/display_server_macos.h
index b4741dc08f..bd3c6af273 100644
--- a/platform/macos/display_server_macos.h
+++ b/platform/macos/display_server_macos.h
@@ -326,7 +326,7 @@ public:
 
 	virtual Vector<int> get_window_list() const override;
 
-	virtual WindowID create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect = Rect2i()) override;
+	virtual WindowID create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect = Rect2i(), bool p_exclusive = false, WindowID p_transient_parent = INVALID_WINDOW_ID) override;
 	virtual void show_window(WindowID p_id) override;
 	virtual void delete_sub_window(WindowID p_id) override;
 
diff --git a/platform/macos/display_server_macos.mm b/platform/macos/display_server_macos.mm
index da45391995..cd2d8a60ac 100644
--- a/platform/macos/display_server_macos.mm
+++ b/platform/macos/display_server_macos.mm
@@ -1714,7 +1714,7 @@ Vector<DisplayServer::WindowID> DisplayServerMacOS::get_window_list() const {
 	return ret;
 }
 
-DisplayServer::WindowID DisplayServerMacOS::create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect) {
+DisplayServer::WindowID DisplayServerMacOS::create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect, bool p_exclusive, WindowID p_transient_parent) {
 	_THREAD_SAFE_METHOD_
 
 	WindowID id = _create_window(p_mode, p_vsync_mode, p_rect);
@@ -1728,6 +1728,12 @@ DisplayServer::WindowID DisplayServerMacOS::create_sub_window(WindowMode p_mode,
 		rendering_device->screen_create(id);
 	}
 #endif
+
+	window_set_exclusive(id, p_exclusive);
+	if (p_transient_parent != INVALID_WINDOW_ID) {
+		window_set_transient(id, p_transient_parent);
+	}
+
 	return id;
 }
 
diff --git a/platform/windows/display_server_windows.cpp b/platform/windows/display_server_windows.cpp
index f29048b16d..1f932b72b0 100644
--- a/platform/windows/display_server_windows.cpp
+++ b/platform/windows/display_server_windows.cpp
@@ -1306,10 +1306,10 @@ DisplayServer::WindowID DisplayServerWindows::get_window_at_screen_position(cons
 	return INVALID_WINDOW_ID;
 }
 
-DisplayServer::WindowID DisplayServerWindows::create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect) {
+DisplayServer::WindowID DisplayServerWindows::create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect, bool p_exclusive, WindowID p_transient_parent) {
 	_THREAD_SAFE_METHOD_
 
-	WindowID window_id = _create_window(p_mode, p_vsync_mode, p_flags, p_rect);
+	WindowID window_id = _create_window(p_mode, p_vsync_mode, p_flags, p_rect, p_exclusive, p_transient_parent);
 	ERR_FAIL_COND_V_MSG(window_id == INVALID_WINDOW_ID, INVALID_WINDOW_ID, "Failed to create sub window.");
 
 	WindowData &wd = windows[window_id];
@@ -5326,7 +5326,7 @@ void DisplayServerWindows::_update_tablet_ctx(const String &p_old_driver, const
 	}
 }
 
-DisplayServer::WindowID DisplayServerWindows::_create_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect) {
+DisplayServer::WindowID DisplayServerWindows::_create_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect, bool p_exclusive, WindowID p_transient_parent) {
 	DWORD dwExStyle;
 	DWORD dwStyle;
 
@@ -5376,6 +5376,18 @@ DisplayServer::WindowID DisplayServerWindows::_create_window(WindowMode p_mode,
 
 	WindowID id = window_id_counter;
 	{
+		WindowData *wd_transient_parent = nullptr;
+		HWND owner_hwnd = nullptr;
+		if (p_transient_parent != INVALID_WINDOW_ID && !windows.has(p_transient_parent)) {
+			ERR_PRINT("Condition \"!windows.has(p_transient_parent)\" is true.");
+			p_transient_parent = INVALID_WINDOW_ID;
+		} else {
+			wd_transient_parent = &windows[p_transient_parent];
+			if (p_exclusive) {
+				owner_hwnd = wd_transient_parent->hWnd;
+			}
+		}
+
 		WindowData &wd = windows[id];
 
 		wd.hWnd = CreateWindowExW(
@@ -5386,7 +5398,7 @@ DisplayServer::WindowID DisplayServerWindows::_create_window(WindowMode p_mode,
 				WindowRect.top,
 				WindowRect.right - WindowRect.left,
 				WindowRect.bottom - WindowRect.top,
-				nullptr,
+				owner_hwnd,
 				nullptr,
 				hInstance,
 				// tunnel the WindowData we need to handle creation message
@@ -5408,6 +5420,12 @@ DisplayServer::WindowID DisplayServerWindows::_create_window(WindowMode p_mode,
 			wd.pre_fs_valid = true;
 		}
 
+		wd.exclusive = p_exclusive;
+		if (wd_transient_parent) {
+			wd.transient_parent = p_transient_parent;
+			wd_transient_parent->transient_children.insert(id);
+		}
+
 		if (is_dark_mode_supported() && dark_title_available) {
 			BOOL value = is_dark_mode();
 			::DwmSetWindowAttribute(wd.hWnd, use_legacy_dark_mode_before_20H1 ? DWMWA_USE_IMMERSIVE_DARK_MODE_BEFORE_20H1 : DWMWA_USE_IMMERSIVE_DARK_MODE, &value, sizeof(value));
@@ -6036,7 +6054,7 @@ DisplayServerWindows::DisplayServerWindows(const String &p_rendering_driver, Win
 		window_position = scr_rect.position + (scr_rect.size - p_resolution) / 2;
 	}
 
-	WindowID main_window = _create_window(p_mode, p_vsync_mode, p_flags, Rect2i(window_position, p_resolution));
+	WindowID main_window = _create_window(p_mode, p_vsync_mode, p_flags, Rect2i(window_position, p_resolution), false, INVALID_WINDOW_ID);
 	ERR_FAIL_COND_MSG(main_window == INVALID_WINDOW_ID, "Failed to create main window.");
 
 	joypad = new JoypadWindows(&windows[MAIN_WINDOW_ID].hWnd);
diff --git a/platform/windows/display_server_windows.h b/platform/windows/display_server_windows.h
index 650f0412ea..7b259def14 100644
--- a/platform/windows/display_server_windows.h
+++ b/platform/windows/display_server_windows.h
@@ -517,7 +517,7 @@ class DisplayServerWindows : public DisplayServer {
 	uint64_t time_since_popup = 0;
 	Ref<Image> icon;
 
-	WindowID _create_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect);
+	WindowID _create_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect, bool p_exclusive, WindowID p_transient_parent);
 	WindowID window_id_counter = MAIN_WINDOW_ID;
 	RBMap<WindowID, WindowData> windows;
 
@@ -652,7 +652,7 @@ public:
 
 	virtual Vector<DisplayServer::WindowID> get_window_list() const override;
 
-	virtual WindowID create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect = Rect2i()) override;
+	virtual WindowID create_sub_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect = Rect2i(), bool p_exclusive = false, WindowID p_transient_parent = INVALID_WINDOW_ID) override;
 	virtual void show_window(WindowID p_window) override;
 	virtual void delete_sub_window(WindowID p_window) override;