Making All Icons Show In The Selection Menu

[VallienFulki]

Is your feature request related to a problem? Please describe.
I'm unsure if this is a bug or not, so I'm making this a feature request for now.

Currently the menu does not show all icons that are installed. This easily gets frustrating when I install Icon Packs, because I can't easily view the pack's contents, and I don't know the exact icons the packs has installed.

Describe the solution you'd like
Being able to have all icons show when selecting an icon from clicking on Change Icon.

When it's an Icon Pack, the icons are placed under the Icon Pack label.
Example
Cool Icons
Icon 1 Icon 2 Icon 3
Icon 4 Icon 5 Icon 6

Describe alternatives you've considered
Currently the wiki does link to the icons used in icon packs. However I would still like to be able to easily see all installed icons in the icon selection menu.