Customizing a dialogs background with QStyle

[yogeshgokul]

Take a look here.
http://doc.trolltech.com/4.5/widgets-styles.html

In This example the custom style class inherited by QMotifStyle. You can derive your style class by QWindowsStyle or any inbuilt style class depending on your basic requirement.

[Giga]

Use QPalette instead.

QPalette palette = dialog.palette();
QLinearGradient gradient(0, 0, 0, 50);
gradient.setColorAt(0, Qt::black);
gradient.setColorAt(1, Qt::white);
QBrush brush(gradient);
palette.setBrush(QPalette::Window, brush);
dialog.setPalette(palette);

QPalette palette = dialog.palette();
QLinearGradient gradient(0, 0, 0, 50);
gradient.setColorAt(0, Qt::black);
gradient.setColorAt(1, Qt::white);
QBrush brush(gradient);
palette.setBrush(QPalette::Window, brush);
dialog.setPalette(palette);

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[yogeshgokul]

Use QPalette instead.

1. The title of this post says that he want to use QStyle.

Customizing a dialogs background with QStyle

2. Qt Docs says:

For example, the following style sheet specifies that all QLineEdits should use yellow as their background color, and all QCheckBoxes should use red as the text color:

QLineEdit { background: yellow }
QCheckBox { color: red }
For this kind of customization, style sheets are much more powerful than QPalette.