Text mark line not seen on black background

[grofaty]

Pinta master on Windows XP:
1. New image 500 x 500.
2. Text from tools and click on canvas.
3. Click on canvas, do not start typing any text.
4. (Observe) You should see black line mark where text is going to be visible. This is OK.
5. Paint Bucket from Tools (make sure black is selected from Palette) and click on canvas to create black background.
6. Repeat steps 2 and 3.
7. (Observe) Black line mark is not seen at all, so it is very difficult to spot where actual text will appear.

[Cameron White (cameronwhite91)]

This isn't a regression, so I think we can leave this until 1.6

[Cameron White (cameronwhite91)]

Fixed: https://github.com/PintaProject/Pinta/commit/e3cca0e7c2f72ed1402ac156a0c4da44160d06c0

The text cursor now just uses the current primary color (i.e. the color of the text). which is an easy way to make sure that the cursor is visible.