FORT WORTH -- Thursday night's 50th-anniversary celebration of the Van Cliburn Competition started with a big surprise -- a shock, really. Just before the music started, out walked Van Cliburn himself, tall and ramrod straight as always. He has been gravely ill with bone cancer, of course, but that didn't keep him away from Bass Hall.Speaking with a slightly unsteady voice, he enumerated some of the things Fort Worth can be proud of: the Fort Worth Symphony Orchestra, conductor Miguel Harth-Bedoya, Bass Hall, the "International Piano Competition" (he didn't mention his own name), the city itself as well as our country.It was a brief speech, and after hugging some of the people onstage, he walked off, turning to wave at the audience and tell them: "I'll love you forever."He got ovations on both his entrance and exit. It was a brave and very touching gesture by Fort Worth's most famous musician.It took a while to get psyched up for the music after that, but it soon became a musically festival occasion.It began with Bach's Concerto in A minor for four keyboards and orchestra. The soloists were, in order of the year of their appearance in the competition: Ralph Votapek, Andre-Michel Schub, Alexander Kobrin and Haochen Zhang.The concerto is pretty much a stunt (one wonders if Bach thought that) but a very high-class stunt originating with two of the world champions of music, Vivaldi (who originated it) and Bach (who arranged it).It was mostly a quick-moving and jolly performance and certainly festive in mood.Kobrin and Schub teamed for Poulenc's Concerto in D minor for two pianos and orchestra. The performance seemed slightly heavy-handed to me, but there was much to enjoy, including Poulenc's way with melody and his salutes to Mozart.Votapek and Zhang (the former is old enough to be the grandfather of the latter, though he stays remarkably youthful) teamed for Mendelssohn's Concerto No. 2 for Two Pianos and orchestra, the most musically satisfactory part of the evening. It's a substantial piece and the two gave it a weighty performance.Part of the street outside Bass Hall was closed for an after-concert celebration, but a deadline kept me from that.Certainly many in the audience must have left with Van Cliburn in their thoughts.