Find tray icons in mounted AppImage

src/main/java/org/cryptomator/ui/traymenu/TrayMenuBuilder.java

@@ -186,7 +186,7 @@ public class TrayMenuBuilder {
 
 	private String getAppropriateFreedesktopIconName() {
 		boolean isAnyVaultUnlocked = vaults.stream().anyMatch(Vault::isUnlocked);
-
-		return isAnyVaultUnlocked ? "org.cryptomator.Cryptomator.tray-unlocked" : "org.cryptomator.Cryptomator.tray";
+		// find tray icons in mounted AppImage
+		return isAnyVaultUnlocked ? System.getenv("APPDIR") + "/usr/share/icons/hicolor/symbolic/apps/org.cryptomator.Cryptomator.tray-unlocked.svg" : System.getenv("APPDIR") + "/usr/share/icons/hicolor/symbolic/apps/org.cryptomator.Cryptomator.tray.svg";
 	}
 }