Currently Catch enables `CATCH_CONFIG_WINDOWS_SEH` only when compiled with MSVC, because some versions of MinGW do not have the necessary Win32 API support.
At this moment, `CATCH_CONFIG_FAST_COMPILE` changes only the behaviour of the `-b` (`--break`) flag, making it break into debugger in a stack frame *below* the actual test, unlike the default behaviour, where the break into debugger occurs in the same stack frame as the actual test. `CATCH_CONFIG_FAST_COMPILE` has to be either defined, or not defined, in all translation units that are linked into single test binary, or the behaviour of setting `-b` flag will be unpredictable.
`CATCH_CONFIG_POSIX_SIGNALS` is on by default, except when Catch is compiled under `Cygwin`, where it is disabled by default (but can be force-enabled by defining `CATCH_CONFIG_POSIX_SIGNALS`).
+`CATCH_CONFIG_WINDOWS_CRTDBG` is off by default. If enabled, Windows's CRT is used to check for memory leaks, and displays them after the tests finish running. _Note that this instrumentation is only done when Catch supplies its own main._
Just as with the C++11 conformance toggles, these toggles can be disabled by using `_NO_` form of the toggle, e.g. `CATCH_CONFIG_NO_WINDOWS_SEH`.