Example is given below to sort detail data block data (toggle asc or desc) with push buttons used as header of grid, by setting ORDER_BY property of data block using SET_BLOCK_PROPERTY command.
The following is the screen shot of this example and this form can be downloaded from the below link:
In this example two data block are being used, one is to contain push buttons to sort data and one is to hold the data in detail block.
On every push button of header the following code is written on When-Button-Pressed trigger:
You see in above example when I am getting the current setting of order by property of the block, I am reading it in upper case because it returns in upper case even if I am setting the property in lower case.