fix left click on buttons

Author: mike-ward

examples/context_menu_demo.v

@@ -82,7 +82,6 @@ fn main_view(mut window gui.Window) gui.View {
 				// ---------------------------------------------------------
 				on_click: fn (_ voidptr, mut e gui.Event, mut w gui.Window) {
 					mut app := w.state[ContextMenuApp]()
-					println(u8(e.mouse_button))
 					if e.mouse_button == .right {
 						app.show_context_menu = true
 						w.set_id_focus(id_focus_context_menu)

view_button.v

@@ -72,7 +72,7 @@ pub fn button(cfg ButtonCfg) View {
 		sizing:       cfg.sizing
 		tooltip:      cfg.tooltip
 		cfg:          &cfg
-		on_click:     cfg.on_click
+		on_click:     cfg.left_click()
 		on_char:      cfg.on_char_button
 		amend_layout: cfg.amend_layout
 		on_hover:     cfg.on_hover
@@ -92,6 +92,17 @@ pub fn button(cfg ButtonCfg) View {
 	)
 }
 
+fn (cfg &ButtonCfg) left_click() fn (&ButtonCfg, mut Event, mut Window) {
+	if cfg.on_click == unsafe { nil } {
+		return cfg.on_click
+	}
+	return fn [cfg] (_ &ButtonCfg, mut e Event, mut w Window) {
+		if e.mouse_button == .left {
+			cfg.on_click(cfg, mut e, mut w)
+		}
+	}
+}
+
 fn (cfg &ButtonCfg) on_char_button(_ &ButtonCfg, mut e Event, mut w Window) {
 	if e.char_code == ` ` && cfg.on_click != unsafe { nil } {
 		cfg.on_click(cfg, mut e, mut w)