doc: testing string for bigger diff example to test

Maybe this input string can be re-used for a potential integration-test?

src/main.zig

@@ -2,7 +2,108 @@
 
 // FIX known issues:
 
-const diff = "";
+const diff =
+\\diff --git a/build.zig.zon b/build.zig.zon
+\\index a039487..944fc49 100644
+\\--- a/build.zig.zon
+\\+++ b/build.zig.zon
+\\@@ -3,8 +3,8 @@
+\\     .version = "0.0.1",
+\\     .dependencies = .{
+\\         .zterm = .{
+\\-            .url = "git+https://gitea.yves-biener.de/yves-biener/zterm#e972a2ea0f7a9f8caffd439ef206474b46475f91",
+\\-            .hash = "zterm-0.3.0-1xmmENkhHAB2rmNJFH-9rRqiRLnT673xwuMrqLwOnlT_",
+\\+            .url = "git+https://gitea.yves-biener.de/yves-biener/zterm#b1a0d60ae379bb91b862d7c4a8a2210cd74c4387",
+\\+            .hash = "zterm-0.3.0-1xmmEMotHACXUXNtsX1P2iz3XQgabNz1PfF7oazYtNam",
+\\         },
+\\     },
+\\     .minimum_zig_version = "0.16.0-dev.1254+bf15c791f",
+\\diff --git a/src/elements.zig b/src/elements.zig
+\\index c0225ae..fb1ad68 100644
+\\--- a/src/elements.zig
+\\+++ b/src/elements.zig
+\\@@ -59,6 +59,7 @@ pub fn Tree(App: type) type {
+\\                 .ptr = this,
+\\                 .vtable = &.{
+\\                     .resize = resize,
+\\+                    .minSize = minSize,
+\\                     .handle = handle,
+\\                     .content = content,
+\\                 },
+\\@@ -70,6 +71,19 @@ pub fn Tree(App: type) type {
+\\             this.size = size;
+\\         }
+\\
+\\+        fn minSize(ctx: *anyopaque, model: *const App.Model, _: Point) Point {
+\\+            // NOTE as we assume the model contents do not change we could calculate the
+\\+            // maximum width required for this `Element` and return that, instead of
+\\+            // calculating the width every time anew. For now this works fine.
+\\+            const this: *@This() = @ptrCast(@alignCast(ctx));
+\\+            const changes: []const Model.Index = model.changes.keys();
+\\+            const files = changes[this.scrollback..];
+\\+            var width: u16 = 0;
+\\+            for (files) |file| width = @max(@as(u16, @intCast(file.len)), width);
+\\+            return .{ .x = width };
+\\+        }
+\\+
+\\+
+\\         fn handle(ctx: *anyopaque, model: *App.Model, event: App.Event) !void {
+\\             const this: *@This() = @ptrCast(@alignCast(ctx));
+\\             switch (event) {
+\\@@ -78,7 +92,17 @@ pub fn Tree(App: type) type {
+\\                     this.scrollback = 0;
+\\                     this.idx = 0;
+\\                 },
+\\-                // TODO also support key inputs to change the current file?
+\\+                .key => |key| {
+\\+                   if (key.eql(.{ .cp = 'J' }) and this.idx < this.len - 1) {
+\\+                       this.idx += 1;
+\\+                       this.queue.push(.{ .file = this.idx });
+\\+                   }
+\\+
+\\+                   if (key.eql(.{ .cp = 'K' }) and this.idx > 0) {
+\\+                       this.idx -= 1;
+\\+                       this.queue.push(.{ .file = this.idx });
+\\+                   }
+\\+                },
+\\                 .mouse => |mouse| if (this.len > 0) switch (mouse.button) {
+\\                     .left => if (mouse.y + this.scrollback < this.len) {
+\\                         this.idx = mouse.y + this.scrollback;
+\\@@ -112,7 +136,6 @@ pub fn Tree(App: type) type {
+\\                 const row_color: zterm.Color = if (this.idx == idx) .blue else .default;
+\\                 cell_idx = row * size.x;
+\\                 for (0..size.x) |_| {
+\\-                    cell_idx += 1;
+\\                     if (value_idx >= value.len) break;
+\\                     const cp = value[value_idx];
+\\                     defer value_idx += 1;
+\\@@ -128,6 +151,7 @@ pub fn Tree(App: type) type {
+\\                         else => cp,
+\\                     };
+\\                     cells[cell_idx].style.fg = row_color;
+\\+                    cell_idx += 1;
+\\                 }
+\\             }
+\\         }
+\\diff --git a/src/root.zig b/src/root.zig
+\\index 29aa832..54d3631 100644
+\\--- a/src/root.zig
+\\+++ b/src/root.zig
+\\@@ -17,7 +17,11 @@ pub fn Container(App: type, gpa: Allocator, element: *elements.Root(App), tree:
+\\             },
+\\         },
+\\     }, element.element());
+\\-    try root.append(try .init(gpa, .{}, tree.element()));
+\\+    try root.append(try .init(gpa, .{
+\\+        .size = .{
+\\+            .grow = .vertical,
+\\+        },
+\\+    }, tree.element()));
+\\     try root.append(try .init(gpa, .{}, .{})); // empty container holding the scrollable element for the diff of each file
+\\     return root;
+\\ }
+\\
+;
 
 pub fn main() !void {
     // argument handling