Sub Grid .open() does not change the [+] into [-]

for (var i = 0; i < dataGrid.getRowsNum(); i++) {
                dataGrid.cellById(dataGrid.getRowId(i), 2).open();

I’m using the above code to open all the sub grids at one on a button click. It opens all the sub grids as expected but [+] change to [-] only in the first sub grid. I have 2 questions;

  1. Am I doing anything wrong in here?
  2. Can I manually(explicitly) change the plus image to minus and vice versa?

Thank you.

Unfortunately your code works well for us locally.
What version of dhtmlx do you have?
Please, open ticket at and provide a complete demo with the reconstructible issue.