[Pidgin] #17174: Rework tray icon blinking.

[Pidgin]

#17174: Rework tray icon blinking.
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 Reporter:  zelch   |      Owner:
     Type:  patch   |     Status:  new
Milestone:          |  Component:  pidgin (gtk)
  Version:  2.11.0  |   Keywords:  tray systray
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 The GTK trey icon blinking API (gtk_status_icon_set_blinking) has been
 depreciated, and there are various reports that the blinking code causes
 problems in some cases.
 (https://github.com/phocean/TopIcons-plus/issues/6)

 These two cases are possibly related, and some testing shows that simply
 not using that API solves at least some problems.

 As such, here is a quick patch that replaces the functionality with a
 slightly different blink feature.

 Note, this makes a couple of obvious UI changes to how blinking works.

 The first, and more obvious, is that it now alternates between the alert
 icon and the non-alert icon, instead of between the alert icon and a blank
 icon.

 The second, and less obvious, is that an alert takes priority of being in
 a connecting state, instead of the other way around. I probably shouldn't
 lump this in, but I consider 'you have a new message' to be more important
 than 'you are connecting'.  If you are both connecting and have a new
 message, it will alternate between the connecting icon and the alert icon.

 The old UI could be approximated by making some blank icon images in the
 different icon sizes.

 I don't have a win32 cross compilation environment setup, so while I think
 I fixed up the win32 code correctly, I'm not going to guarantee that it
 works.

 Regards,
 Zephaniah E. Loss-Cutler-Hull.

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Ticket URL: <https://developer.pidgin.im/ticket/17174>
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