added multisampling (anti-aliasing) support to wxGLCanvas (#9145)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54022 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unix/glx11.h

@@ -66,6 +66,9 @@ public:
     // return GLX version: 13 means 1.3 &c
     static int GetGLXVersion();
 
+    // return true if multisample extension is available
+    static bool IsGLXMultiSampleAvailable();
+
     // get the X11 handle of this window
     virtual Window GetXWindow() const = 0;