Don't use animations when showing non-visible windows.

This is useless anyhow but also results in artefacts when the window becomes
visible later.

Closes #15643.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75130 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775