Created attachment 2644 This file shows the two cases and describes what is desired. It's a bit odd that the border only shows up when you hover it. Perhaps there could be another setting for some type of border that appears at all times. It would be very strange if your Firefox window suddenly opened with no windeco, and this is equally jarring.
I don't really agree, but ultimately this is a matter of aesthetics. I don't find undecorated windows "jarring" at all -- for transient notifications they make quite a lot of sense, and there's plenty of precedent for this. I'd consider adding a style property for this, but it's not high on my prio list right now.
Perhaps I should have been a little more clear why a lack of borders can be jarring. Take for example the following script: notify-send "This is" "A very, very, very, very, very long message" notify-send "Very" "Short" These two notifications will stack, but because there is no border on them and they are different sizes they overlap without a border and it's hard to tell at a glance what text belongs to which -- and they disappear in a few seconds so you don't have much time to decipher this. Thanks for considering the option.
Well, the fact that they overlap isn't relevant -- they aren't supposed to overlap, but proper placement hasn't been implemented yet (but it's *almost* there).
Created attachment 4484 patch to add borders to unhovered notifications. Please add this option. Notifications without borders cannot be distinguished from windows with certain color themes. Also it wouldn't hurt to have this as an option since one could set any desired color. Here is an example patch that does the trick. The color of border is set to fg[NORMAL] for unhovered notifications.
Created attachment 4485 patch to add borders to unhovered notifications. More accurate patch with separate option named `default-border-color` and fallback to it if `border-color` is not presented. Won't brake existing configurations.
This is now fixed in git master with commit 41847681d21e0cfa9534bfda13646fa9838b9e7a. You width and the colour of the border of the notification bubble can now be set for the standard bubble. You can also set it to a different value in "hover" mode to produce a visual effect.