[CMake] control order of custom target as a sub-part of a customized KDE build

[Shawn Rutledge]

I am building a KDE control panel plugin, and there is a requirement
to use a different translation mechanism rather than the default Qt
"tr" macros.  So I want to post-process my ui_*.h files to replace
lines like this

        ClearSiteDataDialog->setWindowTitle(tr2i18n("foo", 0));

 with the replacement code like this

        ClearSiteDataDialog->setWindowTitle(Translator::instance().lookupString(CSD_DIALOG_TITLE));

I wrote a python script to do that, and I'm calling it like this from
cmakelists.txt:

cmake_minimum_required (VERSION 2.6.0)
set (CMAKE_VERBOSE_MAKEFILE true)
find_package(KDE4 REQUIRED)
file(GLOB SRC_FILES *.cpp)
set(kcm_my_plugin_PART_SRCS ${SRC_FILES})
message(STATUS "build type ${CMAKE_BUILD_TYPE}")
file(GLOB UI_FILES *.ui)
message(STATUS "ui files ${UI_FILES}")
kde4_add_ui_files(kcm_my_plugin_PART_SRCS ${UI_FILES})
kde4_add_plugin(kcm_my_plugin ${kcm_my_plugin_PART_SRCS}
${LINUX_COMMON_SOURCE} ${COMMON_SOURCE} ${COMMON_SOURCE_IMPL})
target_link_libraries(kcm_my_plugin  ${KDE4_KDEUI_LIBS}
${KDE4_KCMUTILS_LIBS} ${X11_LIBRARIES} kutils)
# post-process the ui_*.h header files AFTER they have been generated
but BEFORE compiling anything
add_custom_target(ui_translate
	COMMAND ${CMAKE_SOURCE_DIR}/tools/convert-tr2-all.py
	WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
ADD_DEPENDENCIES(kcm_my_plugin ui_translate)
ADD_DEPENDENCIES(kcm_my_plugin_automoc ui_translate)


The only trouble is, it tries to call the script at the beginning of
the build process, so the first time I run "make" it fails, and the
second time after the ui_*.h files have been generated it succeeds.
So, I need to control the order somehow, and I haven't dug deep enough
into the KDE4 package to understand how the existing steps are done in
the right order.  I need to append my extra step after the point where
it generates the ui header files from the UI files.  I'm looking for
ideas on what the dependency should be - which target do I depend on
to get it done at the right time?