I am just trying to port my app from 1.46 to 1.51 to give 1.51 a try. I’ve noticed that many functions have changed from using int’s as parameters to returning Point (such as Component::getMouseXYRelative()). I don’t understand why the old functions haven’t been kept (apart from the new ones?). I’ve literally been spending hours now (the whole morning) just to adapt code to 1.51, which a) is time-consuming b) makes code look ugly and unreadable (because of so many #if 's to cope with 1.46 and 1.51). Wouldn’t it make sense to keep the old functions, too, so it’s easier to port?

Yes, sorry about that. I considered keeping the old functions, but having so many duplicated functions would have led to a lot of code repetition and bloat.

I’ve tried to make the changes fairly gradual, so that each new version doesn’t contain too many differences from the last - but as you’re moving from such an old version, you’re getting hit by a couple of years’ worth of changes all at once!

Great! Even code produced by the old Jucer doesn’t work anymore with the tip! (Just an example: ImageCache::release() does not exist anymore).
What are people supposed to do now? Modify the code created by JUCER after each Save?

no… just load and re-save the files using the latest version of the jucer.