C++ (Qt)
class FadLineEdit : public QLineEdit
{
    Q_OBJECT
 
public:
    enum Side { None, Left, Right };
 
public:
    FadLineEdit( QWidget * parent = 0 );
 
    void addButton( QAbstractButton * button, Side side = Right );
    QAbstractButton * removeButton( QAbstractButton * button, Side side = Right );
 
    QList < QAbstractButton * > * leftSideButtons();
    QList < QAbstractButton * > * rightSideButtons();
 
    Side sideButton( QAbstractButton * button );
 
private:
    void refreshTextMargins();
 
protected:
    QList < QAbstractButton * > d_leftSideButtons;
    QList < QAbstractButton * > d_rightSideButtons;
 
    QHBoxLayout leftSideLayout;
    QHBoxLayout rightSideLayout;
};
 

C++ (Qt)
/// PUBLIC
FadLineEdit::FadLineEdit( QWidget * parent )
    : QLineEdit( parent )
{
    QHBoxLayout * mainLayout = new QHBoxLayout();
    setLayout( mainLayout );
 
    leftSideLayout.addStretch();
    rightSideLayout.addStretch();
 
    leftSideLayout.setSpacing( 0 );
    leftSideLayout.setContentsMargins( 0, 0, 0, 0 );
 
    rightSideLayout.setSpacing( 0 );
    rightSideLayout.setContentsMargins( 0, 0, 0, 0 );
 
    mainLayout->setSpacing( 0 );
    mainLayout->setMargin( 0 );
    mainLayout->addLayout( &leftSideLayout );
    mainLayout->addLayout( &rightSideLayout );
}
 
void FadLineEdit::addButton( QAbstractButton * button, Side side )
{
    if ( side == Right )
    {
        d_rightSideButtons << button;
        rightSideLayout.insertWidget( d_rightSideButtons.size(), button, 0, Qt::AlignRight | Qt::AlignCenter );
 
    } else
    {
        d_leftSideButtons << button;
        leftSideLayout.insertWidget( 0, button, 0, Qt::AlignLeft | Qt::AlignCenter );
    }
 
    refreshTextMargins();
}
QAbstractButton * FadLineEdit::removeButton( QAbstractButton * button, Side side )
{
    if ( side == Right )
    {
        if ( d_rightSideButtons.removeOne( button ) )
        {
            rightSideLayout.removeWidget( button );
            button->setParent( 0 );
 
        } else
            return 0;
 
    } else
    {
        if ( d_rightSideButtons.removeOne( button ) )
        {
            leftSideLayout.removeWidget( button );
            button->setParent( 0 );
 
        } else
            return 0;
    }
 
    refreshTextMargins();
    return button;
}
 
QList < QAbstractButton * > * FadLineEdit::leftSideButtons()
{
    return &d_leftSideButtons;
}
QList < QAbstractButton * > * FadLineEdit::rightSideButtons()
{
    return &d_rightSideButtons;
}
 
FadLineEdit::Side FadLineEdit::sideButton( QAbstractButton * button )
{
    Side side = None;
 
    if ( d_leftSideButtons.indexOf( button ) != -1 )
        side = Left;
 
    else if ( d_rightSideButtons.indexOf( button ) != -1 )
        side = Right;
 
    return side;
}
 
/// PRIVATE
void FadLineEdit::refreshTextMargins()
{
    QMargins margins = textMargins();
 
    if ( !d_leftSideButtons.isEmpty() )
        margins.setLeft( leftSideLayout.sizeHint().width() );
 
    if ( !d_rightSideButtons.isEmpty() )
        margins.setRight( rightSideLayout.sizeHint().width() );
 
    setTextMargins( margins );
}