Since the changes of 6ae7aa4443, the
windows were shown when their geometry was restored as a side effect of
calling ::SetWindowPlacement(). This was unexpected and resulted in
flicker on startup, so fix this by explicitly passing SW_HIDE to
SetWindowPlacement() if the window is currently hidden and storing the
real show command inside wxTLW itself, where it will be used when it's
finally shown.
cf20a9ced5