user guide for the multi variables cross section displays

auxdata/docs/userguide/content/controls/MultiVarsCrossSectionControl.html

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+{More with Vertical Cross-section Control}
+
+
+{
+The newly developed feature will allow to add two more cross-section displays to
+the original cross-section display:
+
+
+[ht::cimg  images/CrossSectionControlGui3.png]
+
+The second shows the settings for this display control:
+
+[ht::cimg  images/CrossSectionControlGui4.png]
+
+
+After creating the first vertical cross-sections display, you can add a contour cross-section
+display for a second variable as well as a wind vector cross-section display for a derived variable.
+When working multi variables cross-section displays, we recommend using a color-filled contour display
+or a color-shaded display, and contour displays for the second or the third variables.
+
+
+
+You can add new parameters a number of ways:
+<ul>
+    <li> Through the  [ug::menu Edit {Add Parameter...}] menu.
+    <li> Through the  [ug::menu View Parameters {Add Parameter...}] menu.
+</ul>
+
+The design only allows maximum three cross-section displays. The newly added parameter has a remove
+action that can be applied:
+
+<ul>
+    <li> [ug::menu {Remove}]. Remove the selected parameter.
+</ul>
+
+
+}
+
+{{Newly added Parameter} {In the display control, checkboxes with parameter name are a modal dialogs
+and have all control widgets associated with newly added parameters.}}