Preserve existing selections on row click for CheckboxSelectionModel in grid

[sachindhake]

I am using CheckboxSelectionModel. After selecting some rows, clicking some other cell / row on the grid causes previously selected rows to be unselected.I know there is a checkOnly config option is available but that is only in in ExtJs 3.x versions. Can anyone please let me know how can I achieve this in ExtJs 2.x version ? \

I referred to checkOnly property's source code and found below code, will it work, please suggest.

gridSelectionModel.on('handleMouseDown', Ext.emptyFn);

Thanks in advance.

[sachindhake]

Setting handleMouseDown event handler to empty function as below worked for me

gridSelectionModel.handleMouseDown = Ext.emptyFn;

Thanks