feat(scrollable): make Container scrollable through Element Scrollable

src/input.zig

@@ -60,17 +60,34 @@ pub const Key = packed struct {
     /// ```zig
     /// switch (event) {
     ///     .quit => break,
-    ///     .key => |key| {
-    ///         // ctrl+c to quit
-    ///         if (key.eql(.{ .cp = 'c', .mod = .{ .ctrl = true } }))
-    ///             app.quit.set();
-    ///     },
+    ///     .key => |key| if (key.eql(.{ .cp = 'c', .mod = .{ .ctrl = true } })) app.quit.set(),
     ///     else => {},
     /// }
     /// ```
     pub fn eql(this: @This(), other: @This()) bool {
         return std.meta.eql(this, other);
     }
+
+    /// Determine if the `Key` is an ascii character that can be printed to
+    /// the screen. This means that the code point of the `Key` is an ascii
+    /// character between 32 - 255 (with the exception of 127 = Delete) and no
+    /// modifiers (alt and/or ctrl) are used.
+    ///
+    /// # Example
+    ///
+    /// Get user input's from the .key event from the application event loop:
+    ///
+    /// ```zig
+    /// switch (event) {
+    ///   .key => |key| if (key.isAscii()) try this.input.append(key.cp),
+    ///   else => {},
+    /// }
+    /// ```
+    pub fn isAscii(this: @This()) bool {
+        return this.mod.alt == false and this.mod.ctrl == false and // no modifier keys
+            (this.cp >= 32 and this.cp <= 126 or // ascii printable characters (except for input.Delete)
+            this.cp >= 128 and this.cp <= 255); // extended ascii codes
+    }
 };
 
 // codepoints for keys