add(Layout/Padding): clear only when necessary

src/layout/Padding.zig

@@ -21,6 +21,7 @@ pub fn Layout(comptime Event: type, comptime Element: type, comptime Renderer: t
     const Events = std.ArrayList(Event);
     return struct {
         size: terminal.Size = undefined,
+        require_render: bool = false,
         element: Element = undefined,
         events: Events = undefined,
         config: Config = undefined,
@@ -60,6 +61,7 @@ pub fn Layout(comptime Event: type, comptime Element: type, comptime Renderer: t
             switch (event) {
                 .resize => |size| {
                     this.size = size;
+                    this.require_render = true;
                     log.debug("Event .resize: {{ .anchor = {{ .col = {d}, .row = {d} }}, .cols = {d}, .rows = {d} }}", .{
                         size.anchor.col,
                         size.anchor.row,
@@ -123,6 +125,11 @@ pub fn Layout(comptime Event: type, comptime Element: type, comptime Renderer: t
         }
 
         pub fn render(this: *@This(), renderer: *Renderer) !void {
+            if (this.require_render) {
+                try renderer.clear(this.size);
+                this.require_render = false;
+            }
+
             switch ((&this.element).*) {
                 .layout => |*layout| {
                     try layout.render(renderer);

src/main.zig

@@ -81,7 +81,7 @@ pub fn main() !void {
                                 var padding = Layout.Padding.init(
                                     allocator,
                                     .{
-                                        .padding = 1,
+                                        .padding = 3,
                                     },
                                     .{
                                         .layout = Layout.createFrom(vstack: {