add:  SetElementEnabledById( "ok", enable); 
context: function ChangeText(){  // Set OK button enable state only if inserting a new link  // (allow empty location to remove existing link)  if (insertNew)  {    var enable = true;    if (insertLinkAtCaret)      enable = dialog.linkTextInput.value.trimString().length > 0;    if (enable)      enable = dialog.hrefInput.value.trimString().length > 0;    SetElementEnabledById( "ok", enable);  }}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/fcbb16c3e306afafb22b5fe59287f397a09ad2b5/EdLinkProps.js/clean/editor/ui/dialogs/content/EdLinkProps.js