Have two different input schemes set up; e.g. Germany/German (default) and English-US/Dvorak.
Per-application switching of input schemes is enabled (Left Alt + Left Shift).
Typing/Composing works as expected.
Switch layout to Dvorak with LAlt+LShift.
Typing now results in characters corresponding to the new layout.
BUG: Composing still uses the German layout when evaluating key strokes within compose sequences.
This may well also affect macro expansion.