ui: Use window decorations on dialog windows (issue #376)

* added SubWindow flag to QtWindow to either use window decorations or show window within main window
* fixes black borders in some Linux window managers

bug id = 376

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src/lib_gui/qt/element/QtLocationPicker.cpp

@@ -26,7 +26,6 @@ QtLocationPicker::QtLocationPicker(QWidget *parent)
 	m_data->setAttribute(Qt::WA_MacShowFocusRect, 0);
 	m_data->setObjectName("locationField");
 	layout->addWidget(m_data);
-	connect(m_data, SIGNAL(focus()), this, SLOT(handleFocus()));
 
 	m_button = new QtIconButton(
 		(ResourcePaths::getGuiPath().str() + "window/dots.png").c_str(),
@@ -125,11 +124,3 @@ void QtLocationPicker::handleButtonPress()
 		emit locationPicked();
 	}
 }
-
-void QtLocationPicker::handleFocus()
-{
-	if (!m_data->text().size())
-	{
-		handleButtonPress();
-	}
-}