I think there is a minor bug with XDA Premium notifications. Here is what I see on my Desire HD, which has a single LED that is used as both a charging indicator and a notification indicator.
Scenario 1:
1) The phone is not charging (not plugged into anything) and the LED is off
2) I receive an XDA notification for a thread I've subscribed to. I hear the notification sound, but the LED does not flash
3) I do not try to read the notification (specifically do not even touch the status bar menu)
4) Plug in the phone. The LED will be lit because it is charging
5) Unplug the phone. The LED will still be lit (not flashing) until I turn on the screen and touch the status bar menu!
Scenario 2:
1) The phone is already plugged in, so the LED is lit
2) I receive an XDA notification for a thread I've subscribed to. I hear the notification sound, but naturally the LED does not flash because the charge indicator has priority
3) I do not try to read the notification (specifically do not even touch the status bar menu)
4) Unplug the phone. The LED will still be lit (not flashing) until I turn on the screen and touch the status bar menu!
Below is some logcat data for Scenario 1 (XDA notification received while phone is not charging). This info doesn't show up for a normal logcat because I added additional LOG statements to lights.c. It's interesting that all fields of the notification structure are set to 0 except for flashMode. I don't know what it means for the flash On and Off times to both be 0, is that valid? Also in the last debug statement of "FLASH: 0x00000003", the 3 means "blank" as opposed to Green, Amber or Blue.
My guess is that this keeps the LED from changing state, for example, normally when you unplug the phone the LED should turn off, but the code that does this notices that the notification structure wants to flash the LED so it skips turning off the LED. Then because the flashing is not specified properly it does nothing.
05-18 12:31:41.111 E/lights ( 1314): set_light_notifications: notification = 0x00000001
05-18 12:31:41.111 E/lights ( 1314): handle_speaker_battery_locked: battery is off, calling 'set_speaker_light_locked (dev, &g_notification)'
05-18 12:31:41.121 E/lights ( 1314): set_speaker_light_locked: Notification Info: color = 0x00000000, flashMode = 0x00000001, flashOnMS = 0x00000000, flashOffMS = 0x00000000,
brightnessMode = 0x00000000
05-18 12:31:41.121 E/lights ( 1314): set_speaker_light_locked: FLASH: 0x00000003
If I knew an easy, fast way to force XDA notifications I would experiment more, but currently this is the best info I can offer. Hopefully it helps.