[BUG] [RFC] g-i-t and new scalable icons

[Luca Ferretti <elle uca libero it>]

--- Summary ---
SVG icons are used when PNG is more appropriate

--- Description ---
Using stuff in HEAD:
     1. Add trashapplet to a 24px panel. The trash icon is the one @
        24x24
     2. Open panel's properties dialog and increase the panel to 27px.
        The trash icon is the new SVG one, scaled down to 27px
     3. Increase the panel's size to 32px. Now the trash icon is the PNG
        one at 32x32 pixel

You can see the same behavior scaling up and down folder, home and trash
icon on desktop or in a Nautilus windows.

--- Expected Behavior ---
Well, I suppose (and I like comments about it) that at 27px the trash
icon should be the 24x24 PNG scaled up or the 32x32 PNG scaled down. 

But, can we do it?

It seems that something like

        [scalable/filesystems]
        Size=48
        -MinSize=1
        +MinSize=50
        MaxSize=256
        Context=FileSystems
        Type=Scalable

works fine. The SVG image is used only when size is >= 5O pixels, but of
course it works 'cause we have PNG image at 16, 24, 32 and 48 pixels.
What will happen if only 48x48 PNG and SVG images are available in
theme? 

The hicolor (fallback) icon theme uses "Type=Threshold", while GNOME
theme uses "Type=Scalable". I've to investigate and test, but maybe an
alternate solution to this bug could be something like
        
        [24x24/filesystems]
        Size=24
        Context=FileSystems
        Type=Threshold
        Threshold=4

        [scalable/filesystems]
        Size=48
        Context=FileSystems
        Type=Scalable
        MinSize=1
        MaxSize=256
        

For more details about this, see icon theme specs on fd.o 



-- 
Luca Ferretti <elle uca libero it>