PortableApps checks for updates on startup and on request.
If there are many updates and I am on a slow connection, I prefer to update only a few apps at a time.
After checking for updates, window "PortableApps.com Update" pops up
... The checkbox for each available update is checked
... For each update I want to defer, I have to uncheck that checkbox
... On the title line, add a checkbox to select/deselect all available updates
(Position over individual app checkboxes, to the left of "Portable App" column header)
... by current default, all apps' checkboxes are checked, so title line checkbox would be checked
Unchecking checked title line checkbox would uncheck each individual apps' checkbox
Checking unchecked title line checkbox would check each individual apps' checkbox
The option is already there, just right-click.
It can't be added to the UI proper at present due to the way the component that handles the checkbox list is written. We probably wouldn't add it anyway as this is an extreme edge-case functionality-wise. Nearly all users simply update all apps or just want to unselect a single one. Only a literal handful of users out of millions want to select every single app in the app store.
Sometimes, the impossible can become possible, if you're awesome!