function button generates a html+css preset button div with a size of [size_x x size_y]px.
string text expects a value such as "This is a button", etc.
string url expects a value such as "http://blabla.org", or you can do stuff such as "pages/somepageinhere.php?parameter_x=123456", etc.
bool new_window expects a boolean value (true/false) and accordingly opens the link in the same or new window.
int size_x, int size_y expect a number (size in pixels to the width [x] and height [y]). If the size is not set (x, or y is left with 0) the button will have default settings. Which means that it should wrap the text inside and be as big as needed to contain it (it's basically just not limited to a specific size).
<?php echo button("This is a button 128x64px","#",false,128,64); echo button("Another button [0x0]","#",false,0,0); echo button("Link to index.php".icon("_new",0),"index.php",true,100,36); ?>