mod(app): SIG.INT handler for Ctrl-C which issues a .cancel event

src/app.zig

@@ -71,6 +71,12 @@ pub fn App(comptime M: type, comptime E: type) type {
             // -> the signal might not work correctly when hosting the application over ssh!
             this.postEvent(.resize);
         }
+        /// registered INT handler to catch ctrl-c to send a `.cancel`
+        fn handleInt(_: i32) callconv(.c) void {
+            const this: *@This() = @ptrCast(@alignCast(handler_ctx));
+            // NOTE do not quit the application and instead issue a `.cancel` event
+            this.postEvent(.cancel);
+        }
 
         pub fn init(gpa: Allocator, io: std.Io, model: Model) @This() {
             return .{
@@ -92,16 +98,23 @@ pub fn App(comptime M: type, comptime E: type) type {
 
             if (!this.handler_registered) {
                 handler_ctx = this;
+                if (config.altScreen) {
                     posix.sigaction(posix.SIG.WINCH, &.{
                         .handler = .{ .handler = handleWinch },
                         .mask = posix.sigemptyset(),
                         .flags = 0,
                     }, null);
+                }
                 posix.sigaction(posix.SIG.CONT, &.{
                     .handler = .{ .handler = handleCont },
                     .mask = posix.sigemptyset(),
                     .flags = 0,
                 }, null);
+                posix.sigaction(posix.SIG.INT, &.{
+                    .handler = .{ .handler = handleInt },
+                    .mask = posix.sigemptyset(),
+                    .flags = 0,
+                }, null);
                 this.handler_registered = true;
             }