Hi Heino;
I would not rush to install PB 12.5.2 (build 5006). 
As soon as you do - all your custom toolbar settings are killed and you can not get the mappings back. For example, when you add a new icon (built-in or custom) - the InfoMaker or PowerBuilder 12.5.2 main power-bar will shrink to just the EXIT door. Try as you may, the toolbar can not be customized any further - it will show OK in the customization dialog's preview - but, never render on the IDE properly.
Selecting the "Reset" option on the toolbar customizer dialog does reset the preview area OK but again when you exit - the main power-bar is still all messed up.
The only way out of this predicament is to enter the toolbar customization dialog and then select the "Clear" button, then select OK. This wipes out the Power-Bar and it then disappears. However, if you close the IM or PB IDE and then restart - the default Power-Bar comes back!
=> I do not think though that this toolbar behaviour will bode well with PB developers or trial users! 
Regards ... Chris