Wt

The problem occurs when a layout of WGroupBox is a WGridLayout and has a nested layout. Widgets are positioned outside the GroupBox and are invisible.

Here is an example:

Wt::WApplication::instance()->setTheme(std::make_shared<Wt::WBootstrap5Theme>()); // comment out to avoid the problem

auto layout = std::make_unique<Wt::WVBoxLayout>();

auto group = layout->addWidget(std::make_unique<Wt::WGroupBox>("Group"));

auto groupLayout = std::make_unique<Wt::WGridLayout>();

groupLayout->addWidget(std::make_unique<Wt::WLabel>("Label"), 0, 0);

auto buttonsLayout = std::make_unique<Wt::WVBoxLayout>();
buttonsLayout->addWidget(std::make_unique<Wt::WPushButton>("Button"));

groupLayout->addLayout(std::move(buttonsLayout), 0, 1);

group->setLayout(std::move(groupLayout));

auto dialog = std::make_unique<Wt::WDialog>("Dialog");
dialog->contents()->setLayout(std::move(layout));
// Without resizing, the layout isn't right even with the default theme, but widgets are at least visible
dialog->resize(500, 500);
dialog->exec();