使主题色依照DDE主题色改变

因为AUTOMOC不会在编译主程序的时候再对插件接口类进行MOC，所以需要在主程序内加一份一模一样的插件接口类定义。

plugin/dtkplugin/spkdtkplugin.cpp

@@ -1,11 +1,25 @@
 #include <DGuiApplicationHelper>
 #include <DPlatformWindowHandle>
+#include <DPlatformTheme>
 #include "spkdtkplugin_impl.h"
 
 using Dtk::Widget::DPlatformWindowHandle;
 
+void SpkDtkPluginImpl::Initialize()
+{
+  connect(DGuiApplicationHelper::instance()->systemTheme(),
+          &DPlatformTheme::activeColorChanged,
+          this,
+          &SpkDtkPluginImpl::AccentColorChanged);
+}
+
 void SpkDtkPluginImpl::addWindow(QWidget *w, QObject *parent)
 {
   DPlatformWindowHandle *h = new DPlatformWindowHandle(w, parent);
   Q_UNUSED(h);
 }
+
+QColor SpkDtkPluginImpl::GetAccentColor()
+{
+  return DGuiApplicationHelper::instance()->systemTheme()->activeColor();
+}