Having the ability to align dialogs in the actions pain using a variable would allow much better cross platform building.
Example: you may have a dialog you want to show as a "bottom sheet" and align to the bottom of the page on mobile, but on web this makes no sense, you may want it to align to the button clicked to show the dialog.
Right now you have to have the same dialog with a conditional action, which doesn't sound like a big deal, until you have a complex action you are passing into the dialog.... Then the risk of not updating both actions if you need to change something become an issue.