"getQuantizer" and "getDrawer" returns instances of selected quantizer and drawer.
"NonDitherDrawer" should be a singleton.
Rename "ditherDropDownList" to "drawerDropDownList".
Rename "getInstance" to "instance".
Create instances of "WebSafeQuantizer" and "NonDitherDrawer".
Call "Encoder.encode".
"WebSafeQuantizer.quantize" always returns a color-mapping for web-safe colors.
"WebSafeQuantizer" and "NonDitherDrawer" are not singletons.
Show only "WebSafeQuantizer" and "NonDitherDrawer" in drop-down lists.
"image" has not been visible until the input image is loaded.
"outputImage" show the encoded GIF-Image.
"Palette" requires a vector of "RGB"s.
Handle an event of slider's value change to set the opacity of preview for the ouput GIF-Image.
Enable "opacitySlider" after the input file is loaded.
Set 0.0 to "opacitySlider.value" when the input image is loaded.
Disable "opacitySlider" when the input image is loaded or encoded.