Vertically stack the color widget when in dock mode

python/gui/qgscompoundcolorwidget.sip

@@ -14,11 +14,19 @@ class QgsCompoundColorWidget : QgsPanelWidget
 
   public:
 
+    //! Widget layout
+    enum Layout
+    {
+      LayoutDefault, /*!< Use the default (rectangular) layout */
+      LayoutVertical, /*!< Use a narrower, vertically stacked layout */
+    };
+
     /** Constructor for QgsCompoundColorWidget
      * @param parent parent widget
      * @param color initial color for dialog
+     * @param layout widget layout to use
      */
-    QgsCompoundColorWidget( QWidget *parent /TransferThis/ = nullptr, const QColor& color = QColor() );
+    QgsCompoundColorWidget( QWidget *parent /TransferThis/ = nullptr, const QColor& color = QColor(), Layout layout = LayoutDefault );
 
     ~QgsCompoundColorWidget();
 

src/gui/qgscolorbutton.cpp

@@ -96,7 +96,8 @@ void QgsColorButton::showColorDialog()
 {
   if ( QgsPanelWidget* panel = QgsPanelWidget::findParentPanel( this ) )
   {
-    QgsCompoundColorWidget* colorWidget = new QgsCompoundColorWidget( panel, color() );
+    QgsCompoundColorWidget* colorWidget = new QgsCompoundColorWidget( panel, color(), panel->dockMode() ? QgsCompoundColorWidget::LayoutVertical :
+        QgsCompoundColorWidget::LayoutDefault );
     colorWidget->setPanelTitle( mColorDialogTitle );
     colorWidget->setAllowAlpha( mAllowAlpha );
     connect( colorWidget, SIGNAL( currentColorChanged( QColor ) ), this, SLOT( setValidTemporaryColor( QColor ) ) );

src/gui/qgscompoundcolorwidget.cpp

@@ -28,9 +28,9 @@
 #include <QDesktopWidget>
 #include <QMouseEvent>
 #include <QInputDialog>
+#include <QVBoxLayout>
 
-
+QgsCompoundColorWidget::QgsCompoundColorWidget( QWidget *parent, const QColor& color, Layout widgetLayout )
-QgsCompoundColorWidget::QgsCompoundColorWidget( QWidget *parent, const QColor& color )
     : QgsPanelWidget( parent )
     , mAllowAlpha( true )
     , mLastCustomColorIndex( 0 )
@@ -38,6 +38,18 @@ QgsCompoundColorWidget::QgsCompoundColorWidget( QWidget *parent, const QColor& c
 {
   setupUi( this );
 
+  if ( widgetLayout == LayoutVertical )
+  {
+    // shuffle stuff around
+    QVBoxLayout* newLayout = new QVBoxLayout();
+    newLayout->addWidget( mTabWidget );
+    newLayout->addWidget( mSlidersWidget );
+    newLayout->addWidget( mPreviewWidget );
+    newLayout->addWidget( mSwatchesWidget );
+    delete layout();
+    setLayout( newLayout );
+  }
+
   QSettings settings;
 
   mSchemeList->header()->hide();

src/gui/qgscompoundcolorwidget.h

@@ -34,11 +34,19 @@ class GUI_EXPORT QgsCompoundColorWidget : public QgsPanelWidget, private Ui::Qgs
 
   public:
 
+    //! Widget layout
+    enum Layout
+    {
+      LayoutDefault = 0, /*!< Use the default (rectangular) layout */
+      LayoutVertical, /*!< Use a narrower, vertically stacked layout */
+    };
+
     /** Constructor for QgsCompoundColorWidget
      * @param parent parent widget
      * @param color initial color for dialog
+     * @param layout widget layout to use
      */
-    QgsCompoundColorWidget( QWidget *parent = nullptr, const QColor& color = QColor() );
+    QgsCompoundColorWidget( QWidget *parent = nullptr, const QColor& color = QColor(), Layout layout = LayoutDefault );
 
     ~QgsCompoundColorWidget();