cmake(highgui): don't allow multiple builtin backends

diff --git a/modules/highgui/CMakeLists.txt b/modules/highgui/CMakeLists.txt
index 5eb9f5a..bc31b84 100644 (file)
--- a/modules/highgui/CMakeLists.txt
+++ b/modules/highgui/CMakeLists.txt
@@ -141,7 +141,7 @@ endif()
 if(TARGET ocv.3rdparty.win32ui)
   if("win32ui" IN_LIST HIGHGUI_PLUGIN_LIST OR HIGHGUI_PLUGIN_LIST STREQUAL "all")
     ocv_create_builtin_highgui_plugin(opencv_highgui_win32 ocv.3rdparty.win32ui "window_w32.cpp")
-  else()
+  elseif(NOT OPENCV_HIGHGUI_BUILTIN_BACKEND)
     set(OPENCV_HIGHGUI_BUILTIN_BACKEND "WIN32UI")
     list(APPEND highgui_srcs ${CMAKE_CURRENT_LIST_DIR}/src/window_w32.cpp)
     list(APPEND tgts ocv.3rdparty.win32ui)