Rockbox

Behaviour of current SVN version:
If you use a background colour in your viewport tag %V, it'll only be used when no backdrop has been enabled.
When a backdrop is enabled, the defined background colour is ignored and the colour of the backdrop at that position will be used instead.

This patch extends the viewport WPS-Tag with an optional parameter to use the defined background colour even when a backdrop is used or to keep the behaviour as is.

The complete syntax of the extended viewport definition is:
%V|x|y|width|height|font|fg_pattern|bg_pattern|[[bg_use_backdrop]|]

You're allowed to use any of the following variations:

%V|x|y|width|height|font|fg_pattern|bg_pattern|
%V|x|y|width|height|font|fg_pattern|bg_pattern||
%V|x|y|width|height|font|fg_pattern|bg_pattern|1|
In all above variations bg_use_backdrop will be set to 1;
If a backdrop is present, the defined background colour will be ignored and the backdrop colour will be used instead.
This is how the current SVN version works...

%V|x|y|width|height|font|fg_pattern|bg_pattern|0|
bg_use_backdrop will be set to 0;
Even when a backdrop is enabled, bg_pattern will be used as background colour.

Note: the whole feature is (currently) only implemented for 16-bit colour targets!
Other targets won't be affected.

Note2: using bg_use_backdrop=1 will always display the backdrop as background, even when viewports overlap (which is btw. not officially allowed atm.).
BTW, this behaviour is exactly as it is now - I just want to mention it ;)

The patch is made against SVN version 16999...
Comments are welcome!

Enjoy!
Massa