POP Peeper has many ways to notify when new messages arrive (three of which are the following):
1) Desktop Alert
2) Balloon-Tip Alert
3) Skin Notifiers (optional methods of getting notifications instead of the Balloon-Tip Alert)
Each one of these three notifiers are either "Turned-Off" or "Turned-On" by checking the boxes or making the proper selection in the "Notification" settings window that I have illustrated previously in screen-shots on how to do this.
Because you ONLY want to compare two notifiers: 1) the Desktop Alert and 2) the Skin Notifier you installed you do NOT WANT the "Balloon Tip" alert to be enabled -- so you would want to "Turn-Off" the Balloon Tip Notifier in this case of just comparing these two other notifiers.
Each of the Notifiers can be either "Turned On" or "Turned Off" -- you do this by following the steps in the screen-shots you will see further up in this topic and also posted below as a reminder.
You can actually "Turn On" BOTH the Desktop Alert and the Skin Notifier at the same time so they will both POP-UP when new messages arrive and then compare which of the two you like the best (when making this comparison it makes sense to "Turn Off" the Balloon Tip because the Skin Notifier "replaces" the Balloon Tip notifier since they are
BOTH POP Peeper Tray Icon Notifiers). Because they are BOTH Tray Icon Notifiers you would not want both to be "Turned On" at the same time -- so please just "Turn On" (which means doing what is illustrated in the screen-shots below) both the Desktop Alert - that is Select "Display Desktop Alert" from the drop-down and the Skin Notifier - check the "Notification Skin" plugin (as illustrated in the screen-shot below) and keep the the Balloon Tip Notifier "Turned Off".
Again just do the following (select "Display Desktop Alert" and make sure the "Display tray icon Balloon Tip" is unchecked):

- Main Menu - go to "Tools" > "Options" > "Notification" to set this Desktop Alert option (note: select "- No Special Action -" to "Turn Off").
Make sure "Notification Skin" plugin box is checked

- Main Menu - go to "Tools" > "Plugins..." to set the Skin Notifier "ON" (check to use -- uncheck to not use)
which will "Turn On" both the Desktop Alert and the Skin Notifier you previously installed (Note: leave the Balloon Tip "Turned Off" [uchecked]). These two Alerts can be compared at the same time if you wish -- once you decide which of the two you prefer then you can "Turn Off" (disable) the one you do not like as much by either unchecking the "Notification Skin" plugin box to "Turn Off" the Skin Notifier or selecting "- No Special Action -" to "Turn Off" the Desktop Alert.
Again -- keep in mind that both the Skin Notifier plugin and the "Tray Icon Balloon Tip" get displayed from the POP Peeper TRAY ICON and since you will be testing the "Skin Notifier" you will NOT want the "Tray Icon Balloon Tip" to also be getting displayed from the same place that is you would not want both to be getting displayed from the POP Peeper Tray Icon.
Good judgment comes from experience and a lot of that comes from bad judgment. - Will Rogers