Tweak fracviewer.cxx to ignore mousewheel inputs,

which were confusing it and making it sometimes
unresponsive to mouse left or middle button drag
inputs...



git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@10184 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

test/fracviewer.cxx

@@ -331,6 +331,7 @@ void agvSwitchMoveMode(int move)
 
 void agvHandleButton(int button, int state, int x, int y)
 {
+ if (button > GLUT_RIGHT_BUTTON)return;
  if (state == GLUT_DOWN && downb == -1) {  
     lastx = downx = x;
     lasty = downy = y;