[Pidgin] #15741: Make attention button optional

[Pidgin]

#15741: Make attention button optional
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 Reporter:  DaveRichmond  |      Owner:
     Type:  patch         |     Status:  new
Milestone:                |  Component:  pidgin (gtk)
  Version:  2.10.7        |   Keywords:
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 I find that I never intentionally use the "attention!" button in the
 conversation window but somehow manage to often press it accidentally when
 switching between windows.

 As such, I have added an option into preferences (in Interface ->
 Conversation Window) that allows the button to be hidden.  It defaults to
 off, so the standard interface doesn't change at all.  If the option is
 enabled, all that happens is the conversation window doesn't add the
 button into the interface.

 Obviously I'm not particularly familiar with the pidgin code base, so I
 could've done this completely wrong.  Also I'm not overly familiar with
 gtk, so I wasn't sure which callback to hook up to in order to refresh the
 conversation window toolbar if the preference changes (so the previous
 setting remains until a conversation window is reopened).  Anyway, I hope
 this patch isn't too offensive to someone more intimately familiar with
 the codebase.

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Ticket URL: <https://developer.pidgin.im/ticket/15741>
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