yet another new backdrop settings dialog idea

[Brian J. Tarricone]

hi all-

francois and i were talking about another revision of the backdrop 
settings dialog today, and he came up with a cool idea:
http://perso.wanadoo.fr/flc.web/xfce/color_tab.png
http://perso.wanadoo.fr/flc.web/xfce/image_tab.png
we talked about the limitations of that design, and came up with some 
improvements.  unfortunately, there were a few annoyances that we didn't 
work out.

so i was just looking at the images, and letting my mind wander, and 
inspiration struct.  i think this idea is pretty cool, but i want to run 
it by everyone else for an intuitive-ness check before i actually code 
it.  i'm not as cool as francois, so no mockup screenshots.

first of all, collapse the color and image tabs back into one.  put the 
bulk of the controls on the left of the dialog (roughly top to bottom)
- color style
- color1
- color2
- image file add/browse button (with label/entry)
- image style (tile, scale, stretch, etc.)
- global options
- - show (option menu):
- - - same image on each screen (multiscreen only)
- - - static image (selected from the list?)
- - - random image (aka, image list)
- - don't set backdrop (really have to do something with this option)

and then on the right side we have a list box, with the following 
columns:
- screen number (hidden if no multiscreen or if in same img or random 
img mode)
- image filename (not full path, just filename)
- small pixmap showing color and style (solid color, mini-gradient)
- an icon describing the image style (tile, stretch, etc.)

when you click on an image in the listbox, the full path is displayed in 
the label/entry on the left, and the color settings and image style 
settings are set to whatever they should be for that image.  you can 
edit the settings, and they'll both be reflected in the listbox and 
applied immediately.

i haven't totally worked out how to store the data.  MCS for everything 
seems a bit overkill, so for simple changes MCS might just serve to 
provide a notification toggle so xfdesktop can reload stuff (hacky?).  
the actually information would be stored in files (xml? key=val?).  the 
cool thing about this is that you could have multiple lists (i could add 
a control to open a different list file.  by default, xfdesktop could 
keep two list files: one for a random image list, and one for an ordered 
set of images to use on different screens since it's conceivable that 
you might want different lists for the two purposes.  then again, it's 
somewhat unlikely that you'd jump between the two - either you want a 
random list or an ordered list - so one list should be fine.

i was thinking that, if you select "same image on all screens" or 
"static image", a bit of screen space is wasted having a listbox to hold 
a single image.  then it occurred to me that you could keep several 
images in the listbox, and statically set the backdrop to the list item 
that's selected.  if you're the kind of person that likes to switch 
images every now and then, you might like having a list of "favorites" 
to choose from.

so what do people think?  i know this seems like the new-feature kind of 
thing that olivier wants to avoid for now (to focus on bugfixing), but i 
personally consider the lack of a good backdrop settings dialog to be a 
large bug.  if it seems like a good idea, i'll start working on it this 
weekend after i finish up with the icon theming stuff.

	-brian