Correct text position in wxDataViewCustomRenderer::RenderText() in wxGTK.

It simply ignored the passed in rectangle meaning that the text was always
drawn at the top left corner of the cell rectangle.

Also more code cleanup: collect all render call parameters in a single struct
and provide a public function to set them all at once instead of making them
public.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62595 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/private/gdkconv.h

@@ -19,6 +19,14 @@ inline wxRect wxRectFromGDKRect(const GdkRectangle *r)
     return wxRect(r->x, r->y, r->width, r->height);
 }
 
+inline void wxRectToGDKRect(const wxRect& rect, GdkRectangle& r)
+{
+    r.x = rect.x;
+    r.y = rect.y;
+    r.width = rect.width;
+    r.height = rect.height;
+}
+
 } // namespace wxGTKImpl
 
 #endif // _GTK_PRIVATE_GDKCONV_H_