more 0.0.12 fixes

examples/links_scraper.v

@@ -4,7 +4,7 @@ fn main() {
 	html := http.get('https://news.ycombinator.com')
 	mut pos := 0
 	for {
-		pos := html.index_after('https://', pos + 1)
+		pos = html.index_after('https://', pos + 1)
 		if pos == -1 {
 			break
 		}

examples/users_gui/users.v

@@ -9,12 +9,14 @@ const (
 )
 
 struct User {
+mut:
 	first_name string
 	last_name  string
 	age        int
 }
 
 struct Context {
+mut:
 	first_name ui.TextBox
 	last_name  ui.TextBox
 	age        ui.TextBox
@@ -26,6 +28,7 @@ struct Context {
 fn main() {
 	mut ctx := &Context {
 		txt_pos: 10
+		window: 0// TODO
 	}
 	ctx.window = ui.new_window(ui.WinCfg {
 		width: 500