[PyQt] Clarifications on new versions of SIP/PyQt

[Giovanni Bajo]

Hi Phil,

I read in the SIP 4.10 changelog:

Added the -P command line option to build modules with "protected"
redefined to "public" if supported by the platform. This can result in
significantly smaller modules.

Can you please elaborate on:

 * What consequences on user's code the -P flag has. Does it break
source code compatibility? What exactly is allowed when the -P flag is
specified, and forbidden otherwise?
 * Why does it affect code size so much?

Also, in PyQt changelog:

Significantly reduced the size of the modules on Linux and MacOS/X.

Is this related to the -P flag above? If so, does it mean that it is
active by default when compiling PyQt on Linux/Mac? If not, how was the
result achieved? Why it does not apply to Windows as well?

Thanks!
-- 
Giovanni Bajo
Develer S.r.l.
http://www.develer.com