Fix layout issues with color button editor widget

- widget was not left aligned
- widget would shrink to a small vertical height in crowded forms

Author: nyalldawson

src/gui/editorwidgets/qgscolorwidgetwrapper.cpp

@@ -14,6 +14,7 @@
  ***************************************************************************/
 
 #include "qgscolorwidgetwrapper.h"
+#include <QLayout>
 
 QgsColorWidgetWrapper::QgsColorWidgetWrapper( QgsVectorLayer* vl, int fieldIdx, QWidget* editor, QWidget* parent )
     : QgsEditorWidgetWrapper( vl, fieldIdx, editor, parent )
@@ -42,14 +43,26 @@ void QgsColorWidgetWrapper::showIndeterminateState()
 
 QWidget* QgsColorWidgetWrapper::createWidget( QWidget* parent )
 {
-  QgsColorButtonV2* button = new QgsColorButtonV2( parent );
+  QWidget* container = new QWidget( parent );
+  QHBoxLayout* layout = new QHBoxLayout();
+  container->setLayout( layout );
+  layout->setMargin( 0 );
+  layout->setContentsMargins( 0, 0, 0, 0 );
+  QgsColorButtonV2* button = new QgsColorButtonV2();
   button->setContext( QString( "editor" ) );
-  return button;
+  layout->addWidget( button );
+  layout->addStretch();
+  container->setSizePolicy( QSizePolicy::Preferred, QSizePolicy::Minimum );
+  return container;
 }
 
 void QgsColorWidgetWrapper::initWidget( QWidget* editor )
 {
   mColorButton = qobject_cast<QgsColorButtonV2*>( editor );
+  if ( !mColorButton )
+  {
+    mColorButton = editor->findChild<QgsColorButtonV2*>();
+  }
 
   connect( mColorButton, SIGNAL( colorChanged( QColor ) ), this, SLOT( valueChanged() ) );
 }