I have found the floodfill bug. If anyone interested:
In the plugins runtime.js, in the flood_fill funtcion the trick below doesn't work on IE:
var color = $('<div></div>').css('background-color', _color).css('background-color').slice(4,-1).split(",");
If you replace the line above with this, it will work fine:
var color = _color.substring(_color.indexOf("(")+1).split(",");
DRAWBACK: you can't pass nice colorname or HSL color parameters, it will work only with rgb(R,G,B) or rgba(R,G,B,A) format.
I admit not the nicest fix, but the floodfill will work in IE too.