Change: replace inputs of type submit with button elements

Attributes 'type="submit"' got removed because it's the default type.
Therefore the attribute can be omitted.

admin/media/select-picture.php

@@ -25,7 +25,7 @@ if($_GET['p']) { ?>
    	    <input id="class" type="text" size="20"></p>
    	 <p><?php echo $l['admin']['pic_alt'] ?><br />
    	    <input id="alt" type="text" size="20"></p>
-   	 <p><input type="submit" value="<?php echo $l['admin']['pic_insert'] ?>"></p>
+   	 <p><button value="<?php echo $l['admin']['pic_insert'] ?>"><?php echo htmlspecialchars($l['admin']['pic_insert']) ?></button></p>
    	 </form>
 <?php
 }