Fix colorpicker slider bug with mouse-up outside of popup

When releasing the mouse button outside of the popup while dragging
a slider, the slider still gets adjusted by mouse-move events.

The reason for this bug is that the mouse-up event is sent to the
focused window (main editor window) instead of the colorpicker
popup window.

This PR adjusts the linuxbsd X11 DisplayServer to send the event to the
correct expected window.

platform/linuxbsd/x11/display_server_x11.cpp

@@ -3929,29 +3929,41 @@ void DisplayServerX11::process_events() {
 				} else {
 					DEBUG_LOG_X11("[%u] ButtonRelease window=%lu (%u), button_index=%u \n", frame, event.xbutton.window, window_id, mb->get_button_index());
 
-					if (!wd.focused) {
+					WindowID window_id_other = INVALID_WINDOW_ID;
+					Window wd_other_x11_window;
+					if (wd.focused) {
+						// Handle cases where an unfocused popup is open that needs to receive button-up events.
+						WindowID popup_id = _get_focused_window_or_popup();
+						if (popup_id != INVALID_WINDOW_ID && popup_id != window_id) {
+							window_id_other = popup_id;
+							wd_other_x11_window = windows[popup_id].x11_window;
+						}
+					} else {
 						// Propagate the event to the focused window,
 						// because it's received only on the topmost window.
 						// Note: This is needed for drag & drop to work between windows,
 						// because the engine expects events to keep being processed
 						// on the same window dragging started.
 						for (const KeyValue<WindowID, WindowData> &E : windows) {
-							const WindowData &wd_other = E.value;
-							WindowID window_id_other = E.key;
-							if (wd_other.focused) {
-								if (window_id_other != window_id) {
-									int x, y;
-									Window child;
-									XTranslateCoordinates(x11_display, wd.x11_window, wd_other.x11_window, event.xbutton.x, event.xbutton.y, &x, &y, &child);
-
-									mb->set_window_id(window_id_other);
-									mb->set_position(Vector2(x, y));
-									mb->set_global_position(mb->get_position());
+							if (E.value.focused) {
+								if (E.key != window_id) {
+									window_id_other = E.key;
+									wd_other_x11_window = E.value.x11_window;
 								}
 								break;
 							}
 						}
 					}
+
+					if (window_id_other != INVALID_WINDOW_ID) {
+						int x, y;
+						Window child;
+						XTranslateCoordinates(x11_display, wd.x11_window, wd_other_x11_window, event.xbutton.x, event.xbutton.y, &x, &y, &child);
+
+						mb->set_window_id(window_id_other);
+						mb->set_position(Vector2(x, y));
+						mb->set_global_position(mb->get_position());
+					}
 				}
 
 				Input::get_singleton()->parse_input_event(mb);