fix WX_GL_STEREO attribute handling: value for it was missing in the attribute list

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@48536 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -229,6 +229,7 @@ wxGTK:
 - Add right button event for wxToolbar's tools (Tim Kosse)
 - Don't unconditionally add wxCAPTION style to wxMiniFrame
 - Generate wxEVT_COMMAND_LIST_END_LABEL_EDIT event even if label didn't change
+- Fix WX_GL_STEREO attribute handling (Tristan Mehamli)
 
 
 2.8.4

src/unix/glx11.cpp

@@ -185,17 +185,21 @@ wxGLCanvasX11::ConvertWXAttrsToGL(const int *wxattrs, int *glattrs, size_t n)
                     glattrs[p++] = GLX_LEVEL;
                     break;
 
+                    // the following boolean attributes don't have values in wx
+                    // API (they're turned on if specified) but do have them in
+                    // OpenGL, so do put them into glattrs and also skip the
+                    // copy of wx value after switch by using "continue"
+                    // instead of "break"
                 case WX_GL_DOUBLEBUFFER:
                     glattrs[p++] = GLX_DOUBLEBUFFER;
                     glattrs[p++] = True;
-
-                    // again, we don't have value for this one in wx list (even
-                    // though OpenGL does use it)
                     continue;
 
                 case WX_GL_STEREO:
                     glattrs[p++] = GLX_STEREO;
-                    break;
+                    glattrs[p++] = True;
+                    continue;
+
 
                 case WX_GL_AUX_BUFFERS:
                     glattrs[p++] = GLX_AUX_BUFFERS;