The main change is to support/ForkedCalls.{h,cpp}. We introduce a static variable IAmAChild and a corresponding accessor. This is set to true in a new fork() method, in the branch taken by the child. (Note: fork() is safe cross-platform, as it just returns -1 if we don't have fork().) This ForkedProcess::iAmAChild() method is then used to protect GuiView::message().
As Abdel has pointed out, there may be other such calls to be protected, e.g., the emission of the Buffer::changed() signal. Those are not addressed here.
git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@22587 a592a061-630c-0410-9148-cb99ea01b6c8
