added docs for new color slider text input

content/docs/user_manual/basic_operations.md

@@ -107,6 +107,10 @@ Each channel can be shown or hidden (eye icon at far left), and its color can be
 
 The three handles on each slider control the range of color mapped to the range of data. The three locks below the sliders will force each of those values to remain in sync across all channel individually.
 
+At the right of each color slider is a button labeled with the number sign `#`. If you click this button, three text boxes will open up showing the value of the corresponding Min/Mid/Max color slider values. In addition, the calculated gamma is shown. You may type new values into these boxes or use the small up/down arrows if you'd like finer control over them. Note that if you type values into the text boxes, the values will become active if you press return/enter, press tab to move to another field, or click the "Set" button at right.
+
+**Note:** While it's impossible to drag the color sliders past each other, it _is_ possible to type values into the text boxes that don't make sense. Sometimes the slider controls will end up on top of each other. In this case, drag the sliders you _can_ access to a new value. The text values will synchronize and update, and you can then enter values that make sense.
+
 At the bottom of the panel to the right of the 2D view area are two color-related buttons. The "Auto Contrast" button attempts to find a reasonable range of colors based on a simple histogram of the data. This almost never does a good job. The "Reset Colors" button returns the displayed color of each channel to its default value (ie, sliders at maximum, etc.). This is also rarely useful.
 
 Note that the current colors, contrast settings, channel visibility and locks are not saved automatically! You must manually save changes by clicking on the gear menu and choosing "Save Color Model To Workspace" or "Save Color Model As User Preference". As the desired settings usually depend on the characteristics of the individual sample, usually you will want to save the color model to the workspace, after which it will be automatically loaded when the workspace is opened. However, if you find there is a baseline color model you'd prefer over the default (sliders set to min/middle/max), you may save to your preferences as a personal default.

content/docs/user_manual/features.md

@@ -307,7 +307,7 @@ Horta 3D has a number of panels containing a variety of supplemental controls. T
     + Center focus, rotation, and zoom: replicate mouse commands 
     + View Slab: adjusts how thick the visible slab of data is; the default preset II shows a nice chunk of data; preset I shows a very thin slab, closely resembling the 2D view 
         * In this pseudo-2D view, hotkeys (shift-A and shift-Z by default) move the camera along the axis into the screen, mimicking scrolling through a z-stack in a 2D view.
-- Color Sliders: used to adjust the color settings for the image data channels and the tracing channel (as described in Horta Basic operation 
+- Color Sliders: used to adjust the color settings for the image data channels and the tracing channel (as described in Horta Basic operation)
 - Movie Maker and Scene Editor: not supported or documented
 - Graphics Speed: used for debugging; displays some graphics performance data