Capture return code

src/freedombone-controlpanel

             app_name=${app_list[app_index]}
             if [[ $app_name == "$AllStr" ]]; then
                 $restore_command
-                if [ ! "$?" = "0" ]; then
+                retcode="$?"
+                if [[ "$retcode" != "0" ]]; then
                     if [[ "$1" == "local" ]]; then
                         dialog --title $"Restore all apps from USB" \
-                               --msgbox $"Restore failed with code $?" 6 40
+                               --msgbox $"Restore failed with code $retcode" 6 40
                     else
                         dialog --title $"Restore all apps from $1" \
-                               --msgbox $"Restore failed with code $?" 6 40
+                               --msgbox $"Restore failed with code $retcode" 6 40
                     fi
                     return
                 fi
             app_name=${app_list[app_index]}
             if [ ${#app_name} -gt 0 ]; then
                 $restore_command "${app_name}"
-                if [ ! "$?" = "0" ]; then
+                retcode="$?"
+                if [[ "$retcode" != "0" ]]; then
                     dialog --title $"Restore apps from USB" \
-                           --msgbox $"Restore of ${app_name} failed with code $?" 6 40
+                           --msgbox $"Restore of ${app_name} failed with code $retcode" 6 40
                     return
                 fi
             fi