Fix app icons in KDE

In KDE, app icons are often replaced with a generic Wayland icon. Since this is both incorrect and horrible, here's a manual way to fix it (on a per-application basis).

  1. When an application window is open, right-click on the titlebar.
  2. Select "More Actions" → "Configure Special Application Settings".
  3. In the window that opens, click the "Add Property" button near the bottom.
  4. In the pop-up, select "Desktop file name".
  5. In the settings of the new property, select "Force" from the dropdown, and enter the name of the .desktop file that includes the correct application settings (i.e., that includes the correct icon). For example, if the relevant .desktop file is located at /usr/share/appliations/my-cool-app.desktop, then enter "my-cool-app" in the text field.
  6. Click the "Apply" and "Okay" buttons at the bottom of the window. The app icon should be changed immediately.