to make them easy to use within an application.
Some dialogs have both platform-dependent and platform-independent implementations,
-so that if underlying windowing systems that do not provide the required functionality,
+so that if underlying windowing systems do not provide the required functionality,
the generic classes and functions can stand in. For example, under MS Windows, wxColourDialog
uses the standard colour selector. There is also an equivalent called wxGenericColourDialog
for other platforms, and a macro defines wxColourDialog to be the same as wxGenericColourDialog