Confused QWidget and QDialog behavior

[munna]

Hi,

I'll try my best to explain things in details

Here is the code I tried

EvlDialog::EvlDialog(QWidget *parent) : QDialog(parent)
{
	setModal(true);
	setAttribute(Qt::WA_DeleteOnClose);
 
	setFixedSize(400,120);
	setAutoFillBackground(true);
 
	//Let us make the edges curved
	QRegion maskRegion(10,10,380,100);
	maskRegion = maskRegion.unite(QRegion(0,10,10,100));//Left
	maskRegion = maskRegion.unite(QRegion(390,10,10,100));//Right
	maskRegion = maskRegion.unite(QRegion(10,0,380,10));//Top
	maskRegion = maskRegion.unite(QRegion(10,110,380,10));//Bottom
 
	maskRegion = maskRegion.unite(QRegion(0,0,20,20,QRegion::Ellipse));//Top-Left
	maskRegion = maskRegion.unite(QRegion(380,0,20,20,QRegion::Ellipse));//Top-Right
	maskRegion = maskRegion.unite(QRegion(0,100,20,20,QRegion::Ellipse));//Bottom-Left
	maskRegion = maskRegion.unite(QRegion(380,100,20,20,QRegion::Ellipse));//Bottom-Right
	setMask(maskRegion);
 
	registerButton = new QPushButton(tr("Enter registraion key"),this);
}

EvlDialog::EvlDialog(QWidget *parent) : QDialog(parent)
{
	setModal(true);
	setAttribute(Qt::WA_DeleteOnClose);

	setFixedSize(400,120);
	setAutoFillBackground(true);

	//Let us make the edges curved
	QRegion maskRegion(10,10,380,100);
	maskRegion = maskRegion.unite(QRegion(0,10,10,100));//Left
	maskRegion = maskRegion.unite(QRegion(390,10,10,100));//Right
	maskRegion = maskRegion.unite(QRegion(10,0,380,10));//Top
	maskRegion = maskRegion.unite(QRegion(10,110,380,10));//Bottom

	maskRegion = maskRegion.unite(QRegion(0,0,20,20,QRegion::Ellipse));//Top-Left
	maskRegion = maskRegion.unite(QRegion(380,0,20,20,QRegion::Ellipse));//Top-Right
	maskRegion = maskRegion.unite(QRegion(0,100,20,20,QRegion::Ellipse));//Bottom-Left
	maskRegion = maskRegion.unite(QRegion(380,100,20,20,QRegion::Ellipse));//Bottom-Right
	setMask(maskRegion);

	registerButton = new QPushButton(tr("Enter registraion key"),this);
}

To copy to clipboard, switch view to plain text mode 

Result
1. No Title Bar (Widget is Frameless)
2. registerButton is clickable.

EvlDialog::EvlDialog(QWidget *parent) : QWidget(parent)
{
	setWindowModality(Qt::WindowModal);
	setAttribute(Qt::WA_DeleteOnClose);
 
	setFixedSize(400,120);
	setAutoFillBackground(true);
 
	//Let us make the edges curved
	QRegion maskRegion(10,10,380,100);
	maskRegion = maskRegion.unite(QRegion(0,10,10,100));//Left
	maskRegion = maskRegion.unite(QRegion(390,10,10,100));//Right
	maskRegion = maskRegion.unite(QRegion(10,0,380,10));//Top
	maskRegion = maskRegion.unite(QRegion(10,110,380,10));//Bottom
 
	maskRegion = maskRegion.unite(QRegion(0,0,20,20,QRegion::Ellipse));//Top-Left
	maskRegion = maskRegion.unite(QRegion(380,0,20,20,QRegion::Ellipse));//Top-Right
	maskRegion = maskRegion.unite(QRegion(0,100,20,20,QRegion::Ellipse));//Bottom-Left
	maskRegion = maskRegion.unite(QRegion(380,100,20,20,QRegion::Ellipse));//Bottom-Right
	setMask(maskRegion);
 
	registerButton = new QPushButton(tr("Enter registraion key"),this);
}

EvlDialog::EvlDialog(QWidget *parent) : QWidget(parent)
{
	setWindowModality(Qt::WindowModal);
	setAttribute(Qt::WA_DeleteOnClose);

	setFixedSize(400,120);
	setAutoFillBackground(true);

	//Let us make the edges curved
	QRegion maskRegion(10,10,380,100);
	maskRegion = maskRegion.unite(QRegion(0,10,10,100));//Left
	maskRegion = maskRegion.unite(QRegion(390,10,10,100));//Right
	maskRegion = maskRegion.unite(QRegion(10,0,380,10));//Top
	maskRegion = maskRegion.unite(QRegion(10,110,380,10));//Bottom

	maskRegion = maskRegion.unite(QRegion(0,0,20,20,QRegion::Ellipse));//Top-Left
	maskRegion = maskRegion.unite(QRegion(380,0,20,20,QRegion::Ellipse));//Top-Right
	maskRegion = maskRegion.unite(QRegion(0,100,20,20,QRegion::Ellipse));//Bottom-Left
	maskRegion = maskRegion.unite(QRegion(380,100,20,20,QRegion::Ellipse));//Bottom-Right
	setMask(maskRegion);

	registerButton = new QPushButton(tr("Enter registraion key"),this);
}

To copy to clipboard, switch view to plain text mode 

Result

1. Widget is frameless
2. Button is not clickable. EvlDialog is behaving as if there is another widget on top which is modal.


Can someone please explain the reason for this kind of behavior.
Thanks a lot.