QWidget Overflow - c++

Question

I have a main QGridLayout on the dialog I'm working on. It's split into content-containers (QWidgets with their own QVBoxLayout) of varying sizes, each assigned a particular number of grid-columns within the grid layout (depending on their needs).
Each content-container holds some buttons. Some of these buttons should span across 2 content-containers. The way I'm trying to achieve this is by overflowing these 2-container buttons outside their layout, while keeping the size of the content-containers the same (what it was allocated according to the number of columns within the grid). I have no idea how to go about this, because either the size of the containers changes, or the QWidget doesn't overflow.
Is there a way to set some sort of overflow property on the button, or do I have to just place the buttons on the grid? I'm trying to avoid doing this because I think it could be messy once new requirements arise and I'll have to recalculate their positioning.
Here is an image of what I'm trying to do:
Here is the relevant code:
ModeDialog::ModeDialog(MainWindow *pMainWindow)
: XDialog(pMainWindow, tr("Operating Mode"), true)
{
XDialog::AddButton(tr("Exit"), QDialogButtonBox::AcceptRole);
ConstructStylingFromTemplates();
CSettings* Settings = pMainWindow->GetSettings();
QString SlotString1, SlotString2;
QGridLayout* mp_MainLayout = new QGridLayout();
mp_MainLayout->setContentsMargins(10, 30, 10, 20);
// Construct Channel Group Layouts with Channel Containers
for (int i = 0; i < 3; i++)
{
switch(i)
{
case 0: { SlotString1 = "A"; SlotString2 = "B"; break; }
case 1: { SlotString1 = "C"; SlotString2 = "D"; break; }
case 2: { SlotString1 = "E"; SlotString2 = "F"; break; }
}
QHBoxLayout* ChannelGroupLayout = new QHBoxLayout();
if (CSettings_RR::IsE1T1Channel(Settings, i*2))
{
AddChannelToChannelGroup(ChannelGroupLayout, SlotString1);
AddChannelToChannelGroup(ChannelGroupLayout, SlotString2);
}
else if(CSettings_RR::IsPtpChannel(Settings, i*2))
{
AddChannelToChannelGroup(ChannelGroupLayout, SlotString1);
}
else if(CSettings_RR::IsOtaChannel(Settings, i*2))
{
AddChannelToChannelGroup(ChannelGroupLayout, SlotString1);
}
else
{
continue;
}
mp_MainLayout->addLayout(ChannelGroupLayout, 0, i*2, 1, 2);
}
SetContentLayout(mp_MainLayout);}
void ModeDialog::AddChannelToChannelGroup(QHBoxLayout* ChannelGroupLayout, QString SlotString)
{
QVBoxLayout* ChannelLayout = new QVBoxLayout();
// Add Label to Channel Layout
XLabel* ChannelLabel = new XLabel("Channel " + SlotString, m_textSize, true, Qt::AlignCenter | Qt::AlignVCenter, this);
ChannelLabel->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
ChannelLayout->addWidget(ChannelLabel);
// Add Container to Channel Layout
QWidget* ChannelContainer = new QWidget();
ChannelContainer->setStyleSheet(m_styleSheetChannelContainer);
ChannelLayout->addWidget(ChannelContainer);
//WIP - add buttons to container
QVBoxLayout* ChannelContainerLayout = new QVBoxLayout();
ChannelContainer->setLayout(ChannelContainerLayout);
XPushButton* ModeButton = new XPushButton(tr("CLOCK"), 160, 40, this, true);
ChannelContainerLayout->addWidget(ModeButton);
//WIPEND
// Add Channel Layout to Channel Group Layout
ChannelGroupLayout->addLayout(ChannelLayout);
}

Answer 1

It is not possible to overflow using QWidgets.
But it is possible with QML.
By default, items will overflow and you have to manage their positions and sizes (and z-index to tell who overlaps who) : http://doc.qt.io/qt-5/qtquick-positioning-topic.html
You have to use QML layouts or set the item's parent property clip to true to avoid the overflow.

Answer 2

There is no way to overflow widgets in Qt, not even if you don't use a layout. A widget will always be limited to its parent's bounds.