Python：Traits GUI深色背景

Question

当打开traitsui窗口时，窗口的背景是暗的而不是光（参见附件截图）。我刚试了一个最小的例子：

from traits.api import HasTraits, Str, Float, Range

class Reservoir(HasTraits):
    name = Str
    max_storage = Float(1e6, desc='Maximal storage [hm3]')
    max_release = Float(10, desc='Maximal release [m3/s]')
    head = Float(10, desc='Hydraulic head [m]')
    efficiency = Range(0, 1.)

    def energy_production(self, release):
        ''' Returns the energy production [Wh] for the given release [m3/s]
        '''
        power = 1000 * 9.81 * self.head * release * self.efficiency
        return power * 3600

res = Reservoir()
res.configure_traits()

Screenshot of what I mean

我正在使用pylab后端运行Ubuntu 16.04和qt4。是否有某种方法可以将背景颜色更改为更轻的？