io/key: improve InputOp focus and blur

The existing implementation cannot remove the focus of some widget,
doesn't have an option to focus without display the on-screen keyboard
and it automatically focuses the first InputOp, aggressively.

That change aims to make possible: remove focus from any widget. Add
focus without displaying the on-screen-keyboard/soft keyboard. Don't
automatically focus any widget. Don't recover focus when the widget is
visible again.

Fixes gio#180.

Signed-off-by: Inkeliz <inkeliz@inkeliz.com>

internal/opconst/ops.go

@@ -21,7 +21,8 @@ const (
 	TypePointerInput
 	TypePass
 	TypeKeyInput
-	TypeHideInput
+	TypeKeyFocus
+	TypeKeySoftKeyboard
 	TypePush
 	TypePop
 	TypeAux
@@ -30,25 +31,26 @@ const (
 )
 
 const (
-	TypeMacroLen          = 1 + 4 + 4
-	TypeCallLen           = 1 + 4 + 4
-	TypeTransformLen      = 1 + 4*6
-	TypeLayerLen          = 1
-	TypeRedrawLen         = 1 + 8
-	TypeImageLen          = 1
-	TypePaintLen          = 1
-	TypeColorLen          = 1 + 4
-	TypeLinearGradientLen = 1 + 8*2 + 4*2
-	TypeAreaLen           = 1 + 1 + 4*4
-	TypePointerInputLen   = 1 + 1 + 1
-	TypePassLen           = 1 + 1
-	TypeKeyInputLen       = 1 + 1
-	TypeHideInputLen      = 1
-	TypePushLen           = 1
-	TypePopLen            = 1
-	TypeAuxLen            = 1
-	TypeClipLen           = 1 + 4*4 + 4 + 2 + 4
-	TypeProfileLen        = 1
+	TypeMacroLen           = 1 + 4 + 4
+	TypeCallLen            = 1 + 4 + 4
+	TypeTransformLen       = 1 + 4*6
+	TypeLayerLen           = 1
+	TypeRedrawLen          = 1 + 8
+	TypeImageLen           = 1
+	TypePaintLen           = 1
+	TypeColorLen           = 1 + 4
+	TypeLinearGradientLen  = 1 + 8*2 + 4*2
+	TypeAreaLen            = 1 + 1 + 4*4
+	TypePointerInputLen    = 1 + 1 + 1
+	TypePassLen            = 1 + 1
+	TypeKeyInputLen        = 1
+	TypeKeyFocusLen        = 1 + 1
+	TypeKeySoftKeyboardLen = 1 + 1
+	TypePushLen            = 1
+	TypePopLen             = 1
+	TypeAuxLen             = 1
+	TypeClipLen            = 1 + 4*4 + 4 + 2 + 4
+	TypeProfileLen         = 1
 )
 
 func (t OpType) Size() int {
@@ -66,7 +68,8 @@ func (t OpType) Size() int {
 		TypePointerInputLen,
 		TypePassLen,
 		TypeKeyInputLen,
-		TypeHideInputLen,
+		TypeKeyFocusLen,
+		TypeKeySoftKeyboardLen,
 		TypePushLen,
 		TypePopLen,
 		TypeAuxLen,