Look for an exact match first when setting a video mode on BeOS.

Fixes Bugzilla #370.

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%402246

src/video/bwindow/SDL_sysvideo.cc

@@ -370,6 +370,16 @@ extern "C"
             (current.timing.h_total * current.timing.v_total);
 
         modes = SDL_modelist[((bpp + 7) / 8) - 1];
+
+        bool exactmatch = false;
+        for ( uint32 x = 0; modes[x]; x++ ) {
+            if (modes[x]->w == width && modes[x]->h == height) {
+                exactmatch = true;
+                i = x;
+                break;
+            }
+        }
+        if (!exactmatch) {
             for (i = 0; modes[i] && (modes[i]->w > width) &&
                  (modes[i]->h > height); ++i) {
                 /* still looking */
@@ -377,6 +387,7 @@ extern "C"
             if (!modes[i] || (modes[i]->w < width) || (modes[i]->h < height)) {
                 --i;                /* We went too far */
             }
+        }
         width = modes[i]->w;
         height = modes[i]->h;
         bscreen.GetModeList(&dmodes, &nmodes);