Yes you can, however it is not advisable because 19 components is the maximum number in which users can view when they use 800x600 res screens.
Anways, if you insist

... file: /administrator/menubar.php
Go to line 115 (or somewhere there) and you'll see the following:
Code:
...
$topLevelLimit = 19; //You can get 19 top levels on a 800x600 Resolution
$topLevelCount = 0;
foreach ($comps as $row) {
... Change the value for $topLevelLimit to the number of components you want to display before breaking it to "More Components...".
PS: I haven't tried this before. Just checked it for you. I think it should work.
HTH.