to get a custom-button, which opens the default resource-editor-page, you can do this:
create a new file under core/components/migx/configs/grid/
with filename like: grid.[theConfigName].config.inc.php
this is in this case: grid.childstutorial.config.inc.php
with this content:
<?php
$gridcontextmenus['editArticle']['code']="
m.push({
className : 'editArticle',
text: _('migx.edit'),
handler: 'this.editArticle'
});
m.push('-');
";
$gridcontextmenus['editArticle']['handler'] = 'this.editArticle';
$gridfunctions['this.editArticle'] = "
editArticle: function(btn,e) {
location.href = 'index.php?a='+MODx.request.a+'&id='+this.menu.record.id;
}
";
Now you can choose the new button 'editArticle' in the migx-Configurator under the columnbuttons-tab and uncheck the 'update' - button
that should do it.