remove auto generation of "_cke_pa_"

I want to add an event handler, ondragstart in ckeditor,
but everytime i added ondragstart="alert('abc')" in the tag like : <p ondragstart="alert('abc')"> ,

i view the source code from some developer kits like firebug,
i see <p _cke_pa_ondragstart="alert('abc')">. . . which is not desired. . . .

if there any ways to remove that???