why do buttons don't change color?

[Raccoon29]

Hi everyone.

I'm using Qt4 on Windows and I'm encountering troubles with the buttons colors.
Two questions I have:
1) Even changing the QPalette::Button and QPalette::ButtonText colors of a QPushButton palette, why just the text gets changed and not the background? Do palettes support multiple changes? Here follows the piece of code which changes the palette:

QPalette pal;
  pal.setColor(QPalette::ButtonText, Qt::white);
  pal.setColor(QPalette::Button, Qt::black);
  ui.cmdsounddod->setPalette(pal);

QPalette pal;
  pal.setColor(QPalette::ButtonText, Qt::white);
  pal.setColor(QPalette::Button, Qt::black);
  ui.cmdsounddod->setPalette(pal);

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2) To Qt developers: was this palette approach needed?
Well, I mean, in Qt3 to change a color needed a call to

uiobject->setBackgroundColor(QColor)

uiobject->setBackgroundColor(QColor)

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and now it needs to pass through the palette that I find a bit complex...
I wouldn't be surprised if I miss a quicker way to change a ui object color...

Thank you in advance,
any help is appreciated