In the grid tool, when the X button of the of the opacity slider in the color sub-panel is clicked, the opacity value is reset to 1 instead of 0.5

Steps to reproduce

1. Select the Grid Tool and click on the color preview

2. Click the X button next to the 0.5 value for Opacity

Expected: The Value is reset to 0.5.

Actual: The Value is reset to 1.