I've always thought it impossible to hide multiple resources, but I've recently discovered a workaround which hides up to 10 resources, which whilst far from perfect might help somewhat. Disclaimer: I'm using the beta at the moment, so it's possible this tip only works on the beta. It's worth trying on the release version though.

Here are the steps:
- Open your library in one panel, and Program Settings in another panel.
- Expand the Hidden Resource section of Program Settings.
- Select the resources you want to hide, up to 10. To select multiple resources click on the first, then SHIFT+click on the last. Alternatively, click on the first then CTRL+click on each of the others.
- In the library panel click "Open all in a floating window"
- When the floating window appears, SHIFT+drag one tab into the hidden resources box. Holding the SHIFT key before you click on a tab causes all the tabs to be selected.
- Close the floating window.