Column-Packed RowColumn Class for Motif Library (C)? - c++

Question

I recently asked this question: Horizontally-Drawn RowColumn Class for Motif Library (C)?
In my previous question, I was having trouble getting the xmRowColumnWidgetClass to draw horizontally (row-by-row) instead of vertically (column-by-column). After playing around with it, figured out how to switch to horizontal drawing with the following snippet:
XmNorientation, XmHORIZONTAL,
So the code that creates the xmRowColumnWidgetClass instance now looks like this:
rowColumn = XtVaCreateManagedWidget("rowcolumn",
xmRowColumnWidgetClass,
parentWidget,
XmNnumColumns, 3,
XmNorientation, XmHORIZONTAL,
XmNpacking, XmPACK_COLUMN,
XmNspacing, 6,
NULL);
However, my new problem is that for some reason the XmNnumColumns field is now referring to the number of rows, rather than the actual number of columns. Before adding the XmNorientation, XmHORIZONTAL part, the xmRowColumnWidgetClass instance was drawing the objects from left-to-right but it stayed to 3 columns like it was supposed to. Now, it is staying to 3 rows, occasionally creating a horizontal scrollbar which I do not want. I only want vertical scrolling.
So I need the children of the xmRowColumnWidgetClass instance to be drawn horizontally from top to bottom, but I need it to only put a maximum of 3 per row and thus keep it confined within a certain width.
I tried playing around with the XmNnumColumns field, but things that worked with more children did not work for less children, and vice versa. Sometimes it made it 4 or 5 columns rather than 3, and sometimes it made it 2 columns with the 3rd column completely empty. I encountered many issues like this even when experimenting with things like using XmNpacking, XmPACK_TIGHT rather than XmNpacking, XmPACK_COLUMN and other stuff.
If someone is able to find the official documentation of the xmRowColumnWidgetClass and link it, that would be be greatly appreciated.
To anybody familiar with this library:
How do I create a xmRowColumnWidgetClass instance that draws horizontally (row-by-row) while keeping it to a certain number of columns?
It should be able to handle any number of children and add as many rows as it needs to in order to keep it as exactly 3 columns.
Another group of examples of this library:
https://github.com/spartrekus/Motif-C-Examples
https://github.com/spartrekus/Motif-C-Examples/blob/master/rowcol.c

Answer 1

XmRowColumn was designed to implement the top menubar and all the other menu classes... You are searching for a grid like widget, and so you have to use XmForm read the related question for that.

Answer 2

In short: try the WtTable widget
Longer explanation follows:
The behaviour of XmRowColumn regarding "columns" becoming "rows" when you choose a horizontal configuration is very unfortunate. The alternative of using XmForm instead of XmRowColumn for this purpose is feasible, but however it requires manually setting the children constraints, and even then, it's quite possible that you won't be able to achieve the automatic sizing implemented in XmRowColumn.
By searching today, I found the WtTable widget and it works fine for my purposes. It's "almost" as automatic as XmRowColumn and it doesn't require to set any constraints manually. I tried it in my Motif code, and works fine.
Note however that I said "almost" as automatic. The "almost" is because you need to specify the number of columns and rows, and you need to specify the column and row for each child widget. However, all of this can be automated: you can create a convenience function that internally manages counters for columns and rows, so that you pass a widget to such function and it puts it in the cell it belongs automatically: you can even make that function create a new row in the WtTable when it's needed.