Polytonic Greek characters cannot be composed both ways

In any program using Qt, I can only input polytonic Greek character in one way, unlike in other toolkits, where I can compose them in multiple diacritic orders.

For instance, say I want to type ἄ. In Qt, I can only do this by typing the acute, then the smooth breathing, then α. In GTK and other toolkits, I can type either that or the smooth breathing, then the acute accent. then the α. This applies to all Greek characters having multiple diacritics.