Find the themes

Michel Caillaud (1957 - ) is a famous French problemist, with great ease on composing remarkable problems of every genre, whose problems we have already presented in this blog (241 341). He was repeatedly the winner of the World Contest of Solving Problems and the Judge of many Composition Contests, for example in Rhodes, Greece, in 2007.
He likes to combine themes in his problems.

In this exercise, where the problem contains few pieces (it is a Miniature), there are two themes.

Solve the problem (it is necessary to find the tries also) and write in the comments the key and the two themes.

I will write the solution at the end of this post after a few days.

	(Problem 352) Michel Caillaud, Second Prize, 148 Thematic Tourney Probleemblad 1985 Mate in 2 moves. #2 ( 6 + 1 )
[4S2R/3P4/8/2K5/Q7/8/8/2B4K]

A note by Alkinoos :
Mr Ioannis Garoufalidis proposed this nice problem.

We have received (30-04-2009) the following complete solution from reader I. K. :

Tries: [1. d8=Q? stalemate], [1. d8=B? ( > 2. Rh5 [A]) Kd5! [a]], [1. d8=R? ( > 2. Be3 [B]) Kb6! [b]]

Key : 1. d8=S! (waiting)
1...Kd5 [a] 2. Rh5# [A]
1...Kb6 [b] 2. Be3# [B]
Themes: (1) The four promotions (AUW), and (2) Dombrovskis.