Question: Should we maybe try and add
wxWS_EX_TRANSIENT to the splash screen's style flags?
Don't use this window as an implicit parent for the other windows: this must be used with transient windows as otherwise there is the risk of creating a dialog/frame with this window as a parent which would lead to a crash if the parent is destroyed before the child.
The occasional crashes/freezes seen when dialogs are shown while the splash screen comes up could (maybe, possibly?) result from that very cause, not sure.