Make code ready for wxWidgets compiled against gtk3

CMakeLists.txt

@@ -40,12 +40,12 @@ IF (((${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU") AND
   MESSAGE(STATUS "Compiler has full c++11 support")
 
   # g++ >= 6.0 sets std=c++14 by default
-  IF (NOT ( ${CMAKE_CXX_COMPILER_ID}  STREQUAL "GNU") OR 
+  IF (NOT ( ${CMAKE_CXX_COMPILER_ID}  STREQUAL "GNU") OR
       (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 6.0.0))
     set(CMAKE_CXX_STANDARD 11)
     set(CMAKE_CXX_STANDARD_REQUIRED ON)
   ENDIF()
-  
+
 ELSE()
   CHECK_CXX_COMPILER_FLAG("-std=c++11" HAS_GNU_CXX11_FLAG)
   IF(HAS_GNU_CXX11_FLAG)
@@ -135,7 +135,10 @@ INCLUDE_DIRECTORIES(${CAIRO_INCLUDE_DIRS})
 LINK_DIRECTORIES(${CAIRO_LIBRARY_DIRS})
 
 IF(LINUX)
-  PKG_CHECK_MODULES(GTK REQUIRED gtk+-2.0)
+  STRING(REGEX MATCH "gtk[23]" GTK_VERSION_SENTINEL "${wxWidgets_LIBRARIES}")
+  STRING(REGEX REPLACE "gtk([23])" "gtk+-\\1.0" GTK_PKG_CONFIG_PACKAGE "${GTK_VERSION_SENTINEL}")
+
+  PKG_CHECK_MODULES(GTK REQUIRED ${GTK_PKG_CONFIG_PACKAGE})
   INCLUDE_DIRECTORIES(${GTK_INCLUDE_DIRS})
   LINK_DIRECTORIES(${GTK_LIBRARY_DIRS})
 
@@ -187,4 +190,4 @@ SET( DEST "${CMAKE_CURRENT_BINARY_DIR}/dist" )
 PACKAGE_RULES( "${PROJECT_NAME}" "${ARCH}" "${DEST}" )
 ENDIF()
 
-MESSAGE(STATUS "Using CMAKE_CXX_FLAGS: $ ${CMAKE_CXX_FLAGS}")
+MESSAGE(STATUS "Using CMAKE_CXX_FLAGS: ${CMAKE_CXX_FLAGS}")