We need to hide <xul:panel>s by default for performance reasons. The RefreshDriver calls gtk/nsWindow::GetClientOffset() in a hot loop and causes a lot of communication between us and the XServer. We and up poll()ing and waiting for XServer responses in RefreshDriver::Tick() which regresses performance on Linux by 50-100%.
Add new newtab control file for the customize functionality. Reuse existing panel styling of the search engine panel.
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extra : rebase_source : 77e84fad6997504040831872d80069d024b1d570