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DiffKey TODO list

 [*]   Fix bypassed GUI code in diffkey.C
 [*]   Fix problem with sliders lagging behind by 1 frame
 [*]   Allow switching on and off of each channel
 [*]   Implement desaturation threshold
 [*]   Write documentation
 [ ]   Toggle display of background on and off
 [ ]   Key frame always contains floating point HSV, RGB, and YMV channels
 [ ]   Store key frame on disk
 [ ]   Allow averaging of multiple frames for key
 [ ]   Radial blur of alpha channel
 [ ]   Shrink edges
 [ ]   Remove noise
 [ ]   Implement all global parameters for each channel
 [ ]   All parameters can be turned on and off
 [ ]   Make new icon for DiffKey
 [ ]   Test render farm and SMP support
