【编辑工具-背景】：快速刷新背景色，预览界面无效果。重新进入添加背景功能，也没有效果 -- 优化

PDF Office/PDF Master/Class/PDFTools/Background/New/View/KMAddBackgroundView.swift

@@ -457,7 +457,7 @@ class KMAddBackgroundView: KMBaseXibView, NSComboBoxDelegate {
         tBackground.update()
         self.pdfView.document = document
         
-        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.3) {
+        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.1) {
             self.isAllowReloadDocument = true
         }
     }