Fix initial visual artifacts, option to start hidden

common.go

@@ -81,4 +81,11 @@ type WebView interface {
 	// f must be a function
 	// f must return either value and error or just error
 	Bind(name string, f interface{}) error
+
+	// Show shows the native window if hidden.
+	// It will also restore a minimized window.
+	Show()
+
+	// Hide hides the native window from the screen and taskbar.
+	Hide()
 }

internal/w32/w32.go

@@ -44,6 +44,7 @@ var (
 	User32SetWindowPos       = user32.NewProc("SetWindowPos")
 	User32IsDialogMessage    = user32.NewProc("IsDialogMessage")
 	User32GetAncestor        = user32.NewProc("GetAncestor")
+	User32IsIconic           = user32.NewProc("IsIconic")
 )
 
 const (
@@ -73,7 +74,9 @@ const (
 )
 
 const (
-	SWShow = 5
+	SWHide    = 0
+	SWShow    = 5
+	SWRestore = 9
 )
 
 const (

webview.go

@@ -44,6 +44,7 @@ type browser interface {
 	Eval(script string)
 	NotifyParentWindowPositionChanged() error
 	Focus()
+	Show() error
 }
 
 type webview struct {
@@ -59,11 +60,12 @@ type webview struct {
 }
 
 type WindowOptions struct {
-	Title  string
-	Width  uint
-	Height uint
-	IconId uint
-	Center bool
+	Title       string
+	Width       uint
+	Height      uint
+	IconId      uint
+	Center      bool
+	StartHidden bool
 }
 
 type WebViewOptions struct {
@@ -333,17 +335,37 @@ func (w *webview) CreateWithOptions(opts WindowOptions) bool {
 	)
 	setWindowContext(w.hwnd, w)
 
-	_, _, _ = w32.User32ShowWindow.Call(w.hwnd, w32.SWShow)
 	_, _, _ = w32.User32UpdateWindow.Call(w.hwnd)
 	_, _, _ = w32.User32SetFocus.Call(w.hwnd)
 
 	if !w.browser.Embed(w.hwnd) {
 		return false
 	}
 	w.browser.Resize()
+	if !opts.StartHidden {
+		_, _, _ = w32.User32ShowWindow.Call(w.hwnd, w32.SWShow)
+		_ = w.browser.Show()
+	}
 	return true
 }
 
+func (w *webview) Hide() {
+	_, _, _ = w32.User32ShowWindow.Call(w.hwnd, w32.SWHide)
+}
+
+func (w *webview) Show() {
+	ret, _, _ := w32.User32IsIconic.Call(w.hwnd)
+	isMinimized := ret != 0
+
+	if isMinimized {
+		_, _, _ = w32.User32ShowWindow.Call(w.hwnd, w32.SWRestore)
+	} else {
+		_, _, _ = w32.User32ShowWindow.Call(w.hwnd, w32.SWShow)
+	}
+
+	_ = w.browser.Show()
+}
+
 func (w *webview) Destroy() {
 	_, _, _ = w32.User32PostMessageW.Call(w.hwnd, w32.WMClose, 0, 0)
 }