When using multi-channel layers, sometimes you want to set the Height channel to a negative value, but the slider for it only ever displays positive values. The only way to make get a negative height value is to right-click the slider and punch in the number manually.
Justification
Negative height values are perfectly valid when converted to a normal map, and having to either punch in negative values manually or bend over backward to create indents by overwriting positive values adds unnecessary friction to the workflow.
Implementation Details
The change can be implemented in one of two ways: either simply remap the slider for Height values from -1 to 1, or allow users to remap sliders themselves. Ideally, if the user punches in a manual value outside the range of a slider, the slider should be remapped automatically to accommodate it.
