...so if you want to assign these f**ed privileges anyway, do next:
1. Excuse me for my English =)
2. Go http://www.uuuq.com/user_db.jsp and save its source as 1.htm (for example)
3. Open 1.htm in Notepad or any editor you like
4. Find there a block:
<form action="" method="post">
<fieldset>
<legend>3. Assign Privileges</legend>
<div id="priv-user-db">
<label for="priv-user">Username:</label>
<select id="priv-user" name="user_name"></select>
<label for="priv-db">Database Name:</label>
<select id="priv-db" name="db_tbl"><option value="YOUR_BASE'.*">USER_YOUR_BASE.*</select>
5. Replace with:
<form action="http://www.uuuq.com/user_db.jsp" method="post">
<fieldset>
<legend>3. Assign Privileges</legend>
<div id="priv-user-db">
<label for="priv-user">Username:</label>
<select id="priv-user" name="user_name"><option value="USERNAME">USER_USERNAME</select>
<label for="priv-db">Database Name:</label>
<select id="priv-db" name="db_tbl"><option value="YOUR_BASE'.*">USER_YOUR_BASE.*
</select>

For example:

<form action="http://www.uuuq.com/user_db.jsp" method="post">
<fieldset>
<legend>3. Assign Privileges</legend>
<div id="priv-user-db">
<label for="priv-user">Username:</label>
<select id="priv-user" name="user_name"><option value="root">corax_root</select>
<label for="priv-db">Database Name:</label>
<select id="priv-db" name="db_tbl"><option value="main`.*">corax_main.*
</select>

6. Save, run, press "Assign Privileges"
7. Enjoy

(oh i forgot you must have original http://www.uuuq.com/user_db.jsp page opened and logged in to)

Oh men. I dont understand what problems do you all have... To work with your databases you should:

1. Create databases, usernames, passwords etc FROM ORIGINAL PAGE!

2. Set privileges FROM HACKED PAGE while ORIGINAL PAGE IS OPENED in another window.

3. If you need, delete users from just one more page, hacked by the same way:

<form action="http://www.uuuq.com/user_db.jsp" method="post" onsubmit="return confirm('Are you sure you want to delete the selected user?')">
<fieldset>
<legend>Delete a database user</legend>
<label for="mysql-delete-user">User Account:</label>
<select id="mysql-delete-user" name="user_name"><option value="root">corax_root</select><button type="submit" class="button-delete"><span>Delete</span></button><input type="hidden" name="mode" value="delete_user">
</fieldset>
</form>

(of course, replace corax and root with your account and your user)

4. In any case, after all the steps USERNAMES still WONT BE LISTED on ORIGINAL PAGE!!! You have to remember them!

<legend>3. Assign Privileges</legend>
<div id="priv-user-db">
<label for="priv-user">Username:</label>
<select id="priv-user" name="user_name"><option value="USERNAME" selected>{it's just blank}
</select>
<label for="priv-db">Database Name:</label>
<select id="priv-db" name="db_tbl"><option value="YOUR_BASE'.*">{this is OK}.*

There are currently no privileges granted