[ColorPicker,Traversal] "Custom Color.." hyperlink can only be reached via keyboard when there is a user defined color.

Steps to reprocuce:
1. run HelloColorPicker, open the pallete
2. try to select "Custom Color..." hyperlink via keyboard: arrow keys, tab or shift tab.
The link is not reachable through above keys.

But if there is a user defined color, the link can be reached.
1. run HelloColorPicker, open the pallete and click "Custom Color..."
2. define a new color in the custom color dialog and save
3. open the pallete again, now the user defined color is focused.
4. press right arrow key until the last user defined color(blank) is focused.
5. now press tab, the "Custom Color..." hyperlink is focused.