refine QDockWidget title icon

src/resources/themes/v_moonlight/v_moonlight.qss

@@ -162,11 +162,27 @@ QDockWidget::Title {
 
 QDockWidget::close-button, QDockWidget::float-button {
     border: none;
+    icon-size: $16px;
+    width: $16px;
 }
 
 QDockWidget::close-button:hover, QDockWidget::float-button:hover {
     background: @dockwidget_button_hover_bg;
 }
+
+QDockWidget::close-button {
+    subcontrol-position: top right;
+    subcontrol-origin: margin;
+    position: absolute;
+    top: 0px; right: 0px; bottom: 0px;
+}
+
+QDockWidget::float-button {
+    subcontrol-position: top right;
+    subcontrol-origin: margin;
+    position: absolute;
+    top: 0px; right: $18px; bottom: 0px;
+}
 /* End DockWidget */
 
 /* QPushButton */

src/resources/themes/v_native/v_native.qss

@@ -29,11 +29,27 @@ QDockWidget::Title {
 
 QDockWidget::close-button, QDockWidget::float-button {
     border: none;
+    icon-size: $16px;
+    width: $16px;
 }
 
 QDockWidget::close-button:hover, QDockWidget::float-button:hover {
     background: @dockwidget_button_hover_bg;
 }
+
+QDockWidget::close-button {
+    subcontrol-position: top right;
+    subcontrol-origin: margin;
+    position: absolute;
+    top: 0px; right: 0px; bottom: 0px;
+}
+
+QDockWidget::float-button {
+    subcontrol-position: top right;
+    subcontrol-origin: margin;
+    position: absolute;
+    top: 0px; right: $18px; bottom: 0px;
+}
 /* End DockWidget */
 
 /* QPushButton */

src/resources/themes/v_pure/v_pure.qss

@@ -162,11 +162,27 @@ QDockWidget::Title {
 
 QDockWidget::close-button, QDockWidget::float-button {
     border: none;
+    icon-size: $16px;
+    width: $16px;
 }
 
 QDockWidget::close-button:hover, QDockWidget::float-button:hover {
     background: @dockwidget_button_hover_bg;
 }
+
+QDockWidget::close-button {
+    subcontrol-position: top right;
+    subcontrol-origin: margin;
+    position: absolute;
+    top: 0px; right: 0px; bottom: 0px;
+}
+
+QDockWidget::float-button {
+    subcontrol-position: top right;
+    subcontrol-origin: margin;
+    position: absolute;
+    top: 0px; right: $18px; bottom: 0px;
+}
 /* End DockWidget */
 
 /* QPushButton */