wxWidgets appears to work fine in Windows XP 32bit. 
wxWidgets appears to work fine in Ubuntu 32bit.

However on OSX PPC 10.4.11 and OSX 10.5 there appears to be a couple of issues.
The "multiline allow Enter" window appears to recieve the key press when you press enter as it reports "Enter pressed in control 'enter', but no new line is created in the dialog box. This function works correctly on Windows. 
In the text box on the far right with all the red, blue text etc, the "cyan on blue" text appears to be Cyan on White.
And the link quotation does not appear to be clickable as it is on other OS. The link is not highlighted and nothing is reported in the log window.

On OS-X 10.5 Intel_x86 hardware wxWidgets appears to fail completely