Prior to 1.2, all the links generated by displaytag are Http Get only, which prevented it from being integrated into many web applications. Including ours. Those links includes paging/sorting and exporting links.
I had to solve the problem by using a customized TableTag along with custom javascript code. The solution was applied around the 1st week of December.
However, they must have forgot the export link - it's still get only... Another custom patch...
Well one day I'll have to contribute it back to the open source project. Too busy recently.