uI

import maya.cmds as cmds

#class
class HP_BuildingGenerator(object):

    #constructor function
    def __init__(self):
        self.window = 'BuildingWindow'
        self.title = 'Building Generator'
        self.size = (600, 350)
        self.createWindow()

    #create window function
    def createWindow(self):

        if cmds.window(self.window, exists=True):
            cmds.deleteUI(self.window, window=True)

        self.window = cmds.window(self.window, title=self.title, widthHeight=self.size)

        # define window UI
        self.mainForm = cmds.formLayout(numberOfDivisions = 100);

        self.titleDisplay = cmds.text(label = self.title, align="center", font='boldLabelFont')
        cmds.formLayout(self.mainForm, edit=True, attachForm=(  [self.titleDisplay, 'top', 5],
                                                                [self.titleDisplay, 'left', 5],
                                                                [self.titleDisplay, 'right', 5] ))


        self.titleSeperator = cmds.separator();
        cmds.formLayout(self.mainForm, edit=True, attachControl=[self.titleSeperator, 'top', 10, self.titleDisplay],
                                                  attachForm=([self.titleSeperator, 'left', 5],
                                                              [self.titleSeperator, 'right', 5] ))
        cmds.showWindow();