Applications invariably need to define accelerator keys for actions. Qt fully supports accelerators, for example with QShortcut. Platform defaults for key bindings can also be assigned using QKeySequence::StandardKey.
Here are Microsoft's recommendations for accelerator keys, with comments about the Open Group's recommendations where they exist and differ. For most commands, the Open Group either has no advice or agrees with Microsoft.
If you have conflicting commands (e.g. About and Apply buttons in the same dialog), you must decide for yourself.
There are also a lot of other keys and actions (that use other modifier keys than Alt). See the Microsoft and The Open Group documentation for details.
The Microsoft book has ISBN 0735605661. The corresponding Open Group book is very hard to find, rather expensive and we cannot recommend it. However, if you really want it, firstname.lastname@example.org might be able to help. Ask them for ISBN 1859121047.