How can I add checkbox in the first dhtmlXtreegrid with the same functionality as in dhtmlxtree .
The treegrid supports only two state checkboxes, you can add them as separate column of ch type
mygrid.setColTypes("ch,tree,ro,ro);
>>How can I make the functionality to change the image when I expande the dhtmlxtreegrid node.
There is no such built in functionality, but you can use onOpenEnd event
grid.attachEvent(“onOpenEnd”,function(id,state){
if (state>0) grid.setItemImage(id,“open.gif”);
else grid.setItemImage(id,“close.gif”);
return true;
})