[Qt-interest] QTextEdit::textBackgroundColor() default return black?

[程梁]

Hi, there! I worked on a rich text editor. Then I have a problem.

I have a button to change text background color. If I haven't set
background color, say the default white, the
QTextEdit::textBackgroundColor() always return QColor(1, 0, 0, 0),
that is black. However, the actually color is white by default. How
does this happen? Is it the function's default return value is black?
If so, how can I recognize the default one, or the user set background
color black?

Thank you!

-- 
Cheng Liang
from: chengliang.soft at gmail.com