I'm not sure about which css is applied that disable the selection.

I am using the row selection model and I use Inspect function in the Firebug, see the class for a cell's inner text is using the css:

x-grid3-cell-inner x-grid3-col-NN (NN is the column number of that cell)

Then I add:
"-moz-user-select: text;
 -moz-user-focus: normal;"
to the 'x-grid3-cell-inner' css definition.

But still not able to highlight the cell and select the text.

ANYONE Know the CSS please help