/*!

\page merging_elements_page Merging Elements

\n This functionality allows to merge coincident elements of a mesh
object selectable in the dialog box. Two elements are considered coincident if they are based on the same set of nodes.

\image html mergeelems_ico.png "Merge elements menu button"

<ol>
<li>Choose in the main menu \b Modification -> \b Transformation
  -> <b>Merge elements</b> item. The following dialog box shall
  appear:</li> 

\image html mergeelems_auto.png
<br>
<ul>
<li>\b Name is the name of the mesh object whose elements will be
  merged.</li> 
<li>\b Automatic or \b Manual Mode allows choosing how the elements
  are processed.
</ul>

<li><b>Automatic mode:</b>
<ul>
<li>In the \b Automatic Mode the elements created on the same nodes
  will be merged.</li> 
</ul>
</li>

<li>If the \b Manual Mode is selected, additional controls are
  available:

\image html mergeelems.png
<br>
<ul>
<li>\b Detect button generates the list of coincident elements found
  in the selected object.</li>
<li><b>Coincident elements</b> is a list of groups of elements for
  merging. As result of the operation all elements of each group will
  be replaced by the firts element of the group.
<ul>
<li>\b Remove button deletes the selected group from the list.</li>
<li>\b Add button adds to the list a group of elements selected in the
  viewer with pressed "Shift" key.</li>
<li><b>Select all</b> checkbox selects all groups.</li>
<li><b>Show double elements IDs</b> checkbox shows/hides identifiers of
  elements of selected groups in the 3D viewer.</li>
</ul></li>
<li><b>Edit selected group</b> list allows editing the selected group:
<br><br>
\image html add.png
<center>adds to the group the elements selected in the viewer.</center>
<br>
\image html remove.png
<center>removes from the group the selected elements.</center>
<br>
\image html sort.png
<center>moves the selected element to the first position in the
  group. This means that all other elements of the group will be
  replaced by this one.</center>
<br>
</li>
<li>To confirm your choice click \b Apply or <b>Apply and Close</b> button.</li>
</ul>
</ol>

In this picture you see a triangle which coincides with one of the
elements of the mesh. After we apply <b>Merge Elements</b> functionality, the
triangle will be completely merged with the mesh.

\image html meshtrianglemergeelem1.png

<br><b>See Also</b> a sample TUI Script of a
\ref tui_merging_elements "Merge Elements" operation.

*/