VirtualKeyBoard customized screen

I want to modify the screen for my image VirtualKeyboard but i faced with problem whatever i do the the Virtualkeyboard still taking its default screen defined in image skin.xml

my code looks like this

class VirtualKeyBoard(Screen):
            skin = '<screen name="myVirtualKeyBoard" position="center,center" size="20,20" title="" flags="wfNoBorder"></screen>'
    

   
            def __init__(self, session, title = '', text = '', maxSize = False, visible_width = False, type ='', currPos = 0, allMarked = False):

is There  a way to make VirtualKeyBoard class takes my customized screen without adding  my screen to skin.xml?