Using evince 3.6.1 with any of the Ubuntu theme:
 - open a pdf
 - change the sidebar to annotation
 - select "add"
 - click on the pen icon
 - click somewhere in the pdf
-> you get a note with a yellow border and white background
 - click in it, type some text
-> with adwaita the text is black
-> with light-themes the text is the same yellow as the border, which is not readable on white

Comments from IRC:

<KaL> the annot window is creating a style properties and changing the color and bg color, I have no idea why, though, I don't remember :-P
 see libview/ev-annotation-window.c
 in ev_annotation_window_set_color
 in gtk_style_properties_set
 try removing the color and set only the bg color
looks like a bug to me, I don't think we want to set both the fg and bg color to be the same


I can confirm that dropping the "color" line in that function makes the text being black the Ubuntu theme and fixes the issue