UI: Fix display bug with color property

With the recent change to fix showing color in the color property widget
when using different themes (b8f03791ea7), a bug was introduced:  when
opening filters with a filter that has a color property, it would sort
of "bug out" and recreate over and over.  This is likely due to
something internally with Qt and the stacked layout.  The stacked layout
really is not necessary, so remove the stacked layout and just use the
color label directly.

UI/properties-view.cpp

@@ -1,5 +1,4 @@
 #include <QFormLayout>
-#include <QStackedLayout>
 #include <QScrollBar>
 #include <QLabel>
 #include <QCheckBox>
@@ -651,26 +650,10 @@ void OBSPropertiesView::AddColor(obs_property_t *prop, QFormLayout *layout,
 	colorLabel->setAlignment(Qt::AlignCenter);
 	colorLabel->setToolTip(QT_UTF8(obs_property_long_description(prop)));
 
-	QFrame *backdrop = new QLabel;
-	backdrop->setFrameStyle(QFrame::Sunken | QFrame::Panel);
-	backdrop->setPalette(palette);
-	backdrop->setStyleSheet(
-		"background: qlineargradient(x1:0, y1:0, x2:1, y2:1,"
-			"stop:0 #cccccc, stop:0.45 #cccccc,"
-			"stop:0.55 #444444, stop:1 #444444)");
-	backdrop->setAutoFillBackground(true);
-
-	QStackedLayout *stackLayout = new QStackedLayout;
-	stackLayout->setContentsMargins(0, 0, 0, 0);
-	stackLayout->setStackingMode(QStackedLayout::StackAll);
-
-	stackLayout->addWidget(backdrop);
-	stackLayout->addWidget(colorLabel);
-
 	QHBoxLayout *subLayout = new QHBoxLayout;
 	subLayout->setContentsMargins(0, 0, 0, 0);
 
-	subLayout->addItem(stackLayout);
+	subLayout->addWidget(colorLabel);
 	subLayout->addWidget(button);
 
 	WidgetInfo *info = new WidgetInfo(this, prop, colorLabel);