@ Jordi March
Thanks for sharing. However it needs more work.
You should provide a package (.lpk) for the components, otherwise other users will most likely not get paths set correctly.
Likewise, you should provide a project file (.lpi) for any example program, particularly a complex GUI such as your example, so that paths etc. are set up correctly.
A .lpr is sufficient for, say, a simple console example, but not for the sort of example you give.
You forgot to include the strutils0 unit which your example references, so it does not compile without amendment.
However, since only one concatenation routine from it is used, why not just use the FPC concat() function?
Also the example program you give has a memory leak at line 650 of the UpdateGridEdit routine in the ComboBoxLpkDB unit where you create columns.