Bug 235

Ok, This could be a good enhancement. If the user sets up the style of one layer
style in the symbolizer and does not Apply the style to the currently select
style layer, and accidently selects the duplicate or creates a new style layer
button. The style information is lost.

Here is what I think should happen: 
If the user starts building a style, eg. select a symbol, or color, than the
duplicate button and create style layer should either be:
1) greyed out, and if selected doesn't work
2) don't change the button image, but when selected check if changes have been
made to the current style. If yes than a popup warning could appear, that they
did not apply the change to there current style, "Press ok to ignore and
continue..."

I am sure you guys have other options.