P: Unable to paste a hex value into the Color Picker (Matte Color) in the Save for Web / PNG-8.

When I'm trying to export an image through the 'Save for Web' dialog and I have selected PNG-8 there is an option to select the Matte Color. When I open the color picker for this it does not allow me to paste my copied hex value like all the other color pickers in Photoshop.