from selenium import webdriver
from selenium.webdriver.common.action_chains import ActionChains

def enter_hours(self, cell, amount):
    #Double-click
    actions = ActionChains(self.driver)
    actions.move_to_element(cell)
    actions.double_click(cell)
    actions.perform()

    #Click
    cell.click()

    #Now, when floating input is visible, grab it and use it!
    control  = self.driver.find_element_by_css_selector('.grid-editbox')
    control.send_keys(amount)