Photoshop :: White / Black Color Combination - Layer Mask Editing

Sometimes it appears that the white/black color combination that is automatically selected in layer mask editing may override the selected color combination outside of layer mask editing.
 
Example:
1) Open Photoshop.
2) Select two colors: white/white.
3) Create two blank documents, each with an empty Layer 1.
4) In one document, add a layer mask to Layer 1. The colors should have been automatically switched to black/white as the layer mask is selected.
5) In this document, use the gradient tool to fill the layer mask with black/white.
6) Switch to the other document, and notice that the color selection is again white/white.
7) In this other document, use the gradient tool to fill Layer 1. Notice that the layer is filled with black/white instead of white/white as selected.