Avoid segv when co-editing around SvxColorTabPage.

Avoid segv when co-editing around SvxColorTabPage.

	vcl::Window::ImplCallDeactivateListeners(vcl::Window*)
		vcl/source/window/window.cxx:3403 (discriminator 2)
	vcl::Window::ImplCallDeactivateListeners(vcl::Window*)
		vcl/source/window/window.cxx:3404
	...
	vcl::Window::ImplCallDeactivateListeners(vcl::Window*)
		vcl/source/window/window.cxx:3404
	vcl::Window::ImplAsyncFocusHdl(void*)
		include/rtl/ref.hxx:112
	...
	Dialog::Execute()
		vcl/source/window/dialog.cxx:1056
	virtual thunk to SalInstanceDialog::run()
		vcl/source/app/salvtables.cxx:4924
	AbstractSvxNameDialog_Impl::Execute()
		cui/source/factory/dlgfact.cxx:222
	SvxColorTabPage::ClickAddHdl_Impl(weld::Button&)
		include/rtl/ref.hxx:192

Change-Id: I12a78d65a8e7b8b728dde84f7c51cc19005c9aa6
Signed-off-by: Michael Meeks <michael.meeks@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/131353
Tested-by: Jenkins
(cherry picked from commit 3d347d1e7835104156ff3cce0b5ea05cefa8ba15)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/131588
Reviewed-by: Adolfo Jayme Barrientos <fitojb@ubuntu.com>