code: public function getClassMethods($className) {
  
          if (!isset($this->classMethodCache[$className])) {
  
              $info = array();
  
              $rClass = new ReflectionClass($className);
  
              $currentClass = $rClass;
              $currentClassName = $currentClass->getName();
              $currentMethods = get_class_methods($currentClass->getName());
              $parentClass = $currentClass->getParentClass();
  
              $level = 1;
              while ($parentClass && $level < 6) {
  
                  $parentClassName = $parentClass->getName();
  
                  if (!in_array($currentClassName, array('Mage_Core_Block_Abstract', 'Mage_Core_Block_Template'))) {
                      $parentMethods = get_class_methods($parentClassName);
                      $tmp = array_diff($currentMethods, $parentMethods);
                      $info[$currentClassName] = array();
  
                      // render methods to "methodName($paramter1, $parameter2, ...)"
                      foreach ($tmp as $methodName) {
  
                          $parameters = array();
                          foreach ($currentClass->getMethod($methodName)->getParameters() as $parameter) { /* @var $parameter ReflectionParameter */
                              $parameters[] = '$'. $parameter->getName();
                          }
  
                          if (count($parameters) > 3) {
                              $parameters = array_slice($parameters, 0, 2);
                              $parameters[] = '...';
                          }
  
                          $info[$currentClassName][] = $methodName . '(' . implode(', ', $parameters) . ')';
                      }
                  } else {
                      $info[$currentClassName] = array('(skipping)');
                      $parentMethods = array();
                  }
  
                  $level++;
  
                  $currentClass = $parentClass;
                  $currentClassName = $currentClass->getName();
                  $currentMethods = $parentMethods;
                  $parentClass = $currentClass->getParentClass();
              }
  
              $this->classMethodCache[$className] = $info;
          }
  
          return $this->classMethodCache[$className];
      }
docs: Get block methods (incl. methods of parent classes)
  
  @param string $className
  @return array