316
edits
Changes
Added section on removed overlays
'''(First Draft)'''
The picture beyond Thunderbird version 60 is rather uncertain, given the continued high rate of change in Firefox platform code. We will work with add-on authors in the coming months to determine a viable post-60 add-on strategy. Below are some general thoughts, which if you have programming questions or wish to discuss the future can be posted in the mozilla.dev.apps.thunderbird newsgroup. (, see [[Thunderbird/CommunicationChannels#If_you.27re_a_developer|Communication Channels]] .
Work has been undertaken to keep supporting legacy add-ons "somewhat" in Thunderbird 63 and beyond. We implemented an overlay loader that will load XUL overlays for add-ons but may cause graphical glitches or malfunctions. We're tracking this in {{bug|1476259}}.
__TOC__
== Removed in Thunderbird ==
From Thunderbird version 60, overlays have been progressively removed, in version 63 there are no overlays left in Thunderbird. Due to Thunderbird's own overlay loader, XUL add-ons can still use overlays, but they can of course not overlay the removed Thunderbird overlays any more. For example, if you add-on overlaid mailWindowOverlay.xul, that needs to be changed; in this example you most likely need to overlay messenger.xul now.
== Removed in mozilla61 ==
* insertItemAt and removeItemAt methods from XUL elements. -- Replacement: insertBefore and remove.
