vb.net - Validate if any changes were made in TabPage -

so i'm wondering if can give me idea how something. have tabcontrol in application - load page - tabpage1 - 25-30 fields. on loading data - run loop save each control value .tag. have function called isdirty() checks each control's ctr.tag.tostring <> ctr.text. i'm having hard time figuring out how build quick handler check controls on form. tried using tagpage1.validating, doesn't anything.

my isdirty() function looks this...

    private function isdirty() boolean      isdirty = false      each ctr control in tabpage1.controls         if typeof ctr textbox , ctr.enabled = true             if ctr.tag.tostring <> ctr.text                 isdirty = true             end if         end if         'more if statements comboboxes , such       next     end function 

i'm hoping able plug function in somewhere , call on

 if isdirty()     msgbox "you have made change form"  end if 

do have call on each control's selection changed?

there 2 approaches

1. when of controls not have change event handler, approach seems correct. way, in above code missed exit for, after isdirty = true.
2. when of controls have changed event handler implemented(this case if in design have data models/objects), rather checking changes in loop, prefer check when change made. mean declare form level variable bool changed. controls textbox, combobox, radiobutton, checkbox, etc.. have change event handlers, if change made set changed true.