This is an issue that is logged in our To Do list. I have raised its priority, however I cannot provide a firm estimation when it will be fixed.
You can customize the dialogs of RadImageEditor as shown in the following article in order to configure the correct default colors for the RadColorPickers: http://demos.telerik.com/aspnet-ajax/imageeditor/examples/externaldialogspath/defaultcs.aspx
. Note that no color is selected for Fill Color
by default, however the color picker controls displays it as a white color.