class ExtensionCombo extends Combo {

	protected function onSelected() {
		var_dump($this->getParent());
        }
}

class MenuItemFoo extends UI\MenuItem
{
	public function __construct()
	{
		file_put_contents('debug.log', 'construct MenuItemFoo');
	}
}
$menu = new Menu('File');
// Class created but `__construct` method not called
$menuItem = $menu->append('Foo', MenuItemFoo::class);

class ExtenfionForm extends Form {
	private $childIndex;
	private $childControl;

	public function addChild(string $name, string $label, UI\Control $control, boolean $stretchy=NULL) {

		$this->childIndex[$name] = $this->append($label, $control, $stretchy ?? false);
		$this->childControl[$name] = $control;
	}

	public function getChild(string $name) {

		return ($this->childControl[$name] ?? NULL);
	}
}

2019/03/29 10:34:13 [error] 10940#10692: *101 FastCGI sent in stderr: "PHP Fatal error: Cannot initialize libui: error initializing libui: registering utility window class; code 1410 (0x00000582) 类已存在。

[libui] /dev/shm/BUILD/libui-f56411fde197481c00ad950e1a545452d47efa55/common/control.c:76:uiFreeControl() You have a bug: You cannot destroy a uiControl while it still has a parent. (control: 0x55e1a8db1e20)
Trace/breakpoint trap (core dumped)

    type ext\pcre\php_pcre.def > D:\php-sdk2\phpmaster\vc15\x64\php-7.3.2-src\x64\Release_TS\php7ts.dll.def
    "C:\Program Files (x86)\Windows Kits\10\bin\10.0.17763.0\x64\mc.exe" -h win32\ -r D:\php-sdk2\phpmaster\vc15\x64\php-7.3.2-src\x64\Release_TS\ -x D:\php-sdk2\phpmaster\vc15\x64\php-7.3.2-src\x64\Release_TS\ win32\build\wsyslog.mc

[Wed Jan 23 15:14:08.070325 2019] [core:warn] [pid 12152:tid 744] AH00098: pid file E:/0_env/phpStudy/Apache/logs/httpd.pid overwritten -- Unclean shutdown of previous Apache run?
[Wed Jan 23 15:14:08.196326 2019] [mpm_winnt:notice] [pid 12152:tid 744] AH00455: Apache/2.4.23 (Win32) OpenSSL/1.0.2j mod_fcgid/2.3.9 configured -- resuming normal operations
[Wed Jan 23 15:14:08.196326 2019] [mpm_winnt:notice] [pid 12152:tid 744] AH00456: Server built: Jul  1 2016 16:42:20
[Wed Jan 23 15:14:08.196326 2019] [core:notice] [pid 12152:tid 744] AH00094: Command line: 'E:\\0_env\\phpStudy\\Apache\\bin\\httpd.exe -d E:/0_env/phpStudy/Apache'
[Wed Jan 23 15:14:08.203294 2019] [mpm_winnt:notice] [pid 12152:tid 744] AH00418: Parent: Created child process 5004
[Wed Jan 23 15:14:09.812294 2019] [mpm_winnt:notice] [pid 5004:tid 780] AH00354: Child: Starting 150 worker threads.
[Wed Jan 23 15:14:11.930571 2019] [core:error] [pid 5004:tid 2104] [client ::1:50235] End of script output before headers: index.php

namespace UI;
use UI\Draw\Color;
interface Colourable
{
    public function setBackgroundColor(Color $color): self;
    public function getBackgroundColor(): Color;
    public function setForegroundColor(Color $color): self;
    public function getForegroundColor(): Color;
}

namespace UI;
use UI\Draw\Color;
class Control implements Colourable
{
    protected $backgroundColor = 0x000000;
    protected $foregroundColor = 0xFFFFFF;

    public function setBackgroundColor(Color $color): self
    {
        $this->backgroundColor = $color;
        return $this;
    }
    public function getBackgroundColor()
    {
        if (is_int($this->backgroundColor)) {
            $this->backgroundColor = new Color($this->backgroundColor);
        }
        return $this->backgroundColor;
    }
    public function setForegroundColor(Color $color): self
    {
        $this->foregroundColor = $color;
        return $this;
    }
    public function getForegroundColor()
    {
        if (is_int($this->foregroundColor)) {
            $this->foregroundColor = new Color($this->foregroundColor);
        }
        return $this->foregroundColor;
    }
}

namespace UI;
use UI\Draw\Color;
class Menu implements Colourable
{
    protected $backgroundColor = 0x000000;
    protected $foregroundColor = 0xFFFFFF;

    public function setBackgroundColor(Color $color): self
    {
        $this->backgroundColor = $color;
        return $this;
    }
    public function getBackgroundColor()
    {
        if (is_int($this->backgroundColor)) {
            $this->backgroundColor = new Color($this->backgroundColor);
        }
        return $this->backgroundColor;
    }
    public function setForegroundColor(Color $color): self
    {
        $this->foregroundColor = $color;
        return $this;
    }
    public function getForegroundColor()
    {
        if (is_int($this->foregroundColor)) {
            $this->foregroundColor = new Color($this->foregroundColor);
        }
        return $this->foregroundColor;
    }
}

namespace UI\Controls;

use UI\Control;
use UI\Size;
use Closure;

class Browser extends Control
{
	protected $size;
	protected $onUpdateCallback;
	private $rawHtml = '';
	protected $html = '';
   
	public function __construct(Size $size, callable $onUpdate = null): void
	{
		$this->setSize($size);
		if ($onUpdate !== null) {
			$this->onUpdate($onUpdate);
		} 
	}
    public function setSize(Size $size): self
    {
		$this->size = $size;
		return $this;
    }
    public function getSize(): Size
    {
		return $this->size;
    }
    public function onUpdate(callable $callback): self
    {
		if (!($callback instanceof Closure)) {
			$callback = Closure::fromCallable($callback);
		}
		$this->onUpdateCallback = $callback;
		$this->html = $this->rawHtml;
		return $this->update();
    }
    public function setHtml(string $html): self
    {
		$this->rawHtml = $this->html = $html;
		return $this->update();
    }
    public function getHtml(bool $raw = false): string
    {
		return $raw ? $this->rawHtml : $this->html;
    }
    protected function update(): self
    {
		if ($this->rawHtml && $this->onUpdateCallback) {
			$raw = $this->rawHtml;
			$this->onUpdateCallback->call($this);
			$this->rawHtml = $raw;
		}
		$this->redraw();
		return $this;
    }
    private function redraw(): void
    {
		// Redraw control by $this->html
    }
}

ᐅ ./configure               
checking for grep that handles long lines and -e... /bin/grep
checking for egrep... /bin/grep -E
checking for a sed that does not truncate output... /bin/sed
checking for cc... cc
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
checking for suffix of executables... 
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether cc accepts -g... yes
checking for cc option to accept ISO C89... none needed
checking how to run the C preprocessor... cc -E
checking for icc... no
checking for suncc... no
checking whether cc understands -c and -o together... yes
checking for system library directory... lib
checking if compiler supports -R... no
checking if compiler supports -Wl,-rpath,... yes
checking build system type... x86_64-unknown-linux-gnu
checking host system type... x86_64-unknown-linux-gnu
checking target system type... x86_64-unknown-linux-gnu
checking for PHP prefix... /usr
checking for PHP includes... -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib
checking for PHP extension directory... /usr/lib/php/extensions/no-debug-zts-20160303
checking for PHP installed headers prefix... /usr/include/php
checking if debug is enabled... no
checking if zts is enabled... yes
checking for re2c... re2c
checking for re2c version... 0.16 (ok)
checking for gawk... gawk
checking for ui support... yes, shared
checking for ui threads... no
checking for ui files in default path... not found
configure: error: Please reinstall the ui distribution

/Users/suxiaolin/Downloads/UI-2.0.0/UI-2.0.0/ui.c:331:82: error: too few arguments to function call, expected 3, have 2
                add_next_index_string(return_value, uiDrawFontFamiliesFamily(families, familiy));

Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 8.0.0 (clang-800.0.42.1)
Target: x86_64-apple-darwin15.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

<?php
//Create a new glade instance, load the 
// widgets from the file passed as parameter
$glade = new GladeXML('helloglade.glade');
 
//Start the main loop
Gtk::main();
?>

$bos = new Box(Box::Vertical)
    ->setPadded()
    ->append(new Combo()
        ->append("Item 1")
        ->append("Item 2")
        ->append("Item 3"))
    ->append(new Separator(Separator::Horizontal))
    ...

/bin/sh /usr/local/src/php/ui/libtool --mode=compile cc -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1 -I. -I/usr/local/src/php/ui -DPHP_ATOM_INC -I/usr/local/src/php/ui/include -I/usr/local/src/php/ui/main -I/usr/local/src/php/ui -I/usr/local/php-7.2/include/php -I/usr/local/php-7.2/include/php/main -I/usr/local/php-7.2/include/php/TSRM -I/usr/local/php-7.2/include/php/Zend -I/usr/local/php-7.2/include/php/ext -I/usr/local/php-7.2/include/php/ext/date/lib  -DHAVE_CONFIG_H  -march=native -mtune=native -fdiagnostics-color=auto -O2 -fPIC -pipe   -c /usr/local/src/php/ui/classes/box.c -o classes/box.lo 
 cc -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1 -I. -I/usr/local/src/php/ui -DPHP_ATOM_INC -I/usr/local/src/php/ui/include -I/usr/local/src/php/ui/main -I/usr/local/src/php/ui -I/usr/local/php-7.2/include/php -I/usr/local/php-7.2/include/php/main -I/usr/local/php-7.2/include/php/TSRM -I/usr/local/php-7.2/include/php/Zend -I/usr/local/php-7.2/include/php/ext -I/usr/local/php-7.2/include/php/ext/date/lib -DHAVE_CONFIG_H -march=native -mtune=native -fdiagnostics-color=auto -O2 -fPIC -pipe -c /usr/local/src/php/ui/classes/box.c  -fPIC -DPIC -o classes/.libs/box.o
/usr/local/src/php/ui/classes/box.c:188:91: error: macro "ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX" passed 6 arguments, but takes just 5
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(php_ui_box_is_padded_info, 0, 0, _IS_BOOL, NULL, 0)
                                                                                           ^
In file included from /usr/local/php-7.2/include/php/main/php.h:39,
                 from /usr/local/src/php/ui/classes/box.c:22:
/usr/local/php-7.2/include/php/Zend/zend_API.h:128:30: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘}’ token
 #define ZEND_END_ARG_INFO()  };
                              ^
/usr/local/src/php/ui/classes/box.c:192:1: note: in expansion of macro ‘ZEND_END_ARG_INFO’
 ZEND_END_ARG_INFO()
 ^~~~~~~~~~~~~~~~~
In file included from /usr/local/php-7.2/include/php/main/php.h:39,
                 from /usr/local/src/php/ui/classes/box.c:22:
/usr/local/src/php/ui/classes/box.c:217:31: error: ‘php_ui_box_is_padded_info’ undeclared here (not in a function); did you mean ‘php_ui_box_set_padded_info’?
  PHP_ME(Box, isPadded,        php_ui_box_is_padded_info, ZEND_ACC_PUBLIC)
                               ^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/php-7.2/include/php/Zend/zend_API.h:70:75: note: in definition of macro ‘ZEND_FENTRY’
 #define ZEND_FENTRY(zend_name, name, arg_info, flags) { #zend_name, name, arg_info, (uint32_t) (sizeof(arg_info)/sizeof(struct _zend_internal_arg_info)-1), flags },
                                                                           ^~~~~~~~
/usr/local/php-7.2/include/php/main/php.h:422:25: note: in expansion of macro ‘ZEND_ME’
 #define PHP_ME          ZEND_ME
                         ^~~~~~~
/usr/local/src/php/ui/classes/box.c:217:2: note: in expansion of macro ‘PHP_ME’
  PHP_ME(Box, isPadded,        php_ui_box_is_padded_info, ZEND_ACC_PUBLIC)
  ^~~~~~
make: *** [Makefile:207: classes/box.lo] Error 1

downloading UI-2.0.0.tgz ...
Starting to download UI-2.0.0.tgz (49,498 bytes)
.............done: 49,498 bytes
79 source files, building
running: phpize
Configuring for:
PHP Api Version:         20170718
Zend Module Api No:      20170718
Zend Extension Api No:   320170718
building in /tmp/pear/temp/pear-build-root48Co5t/UI-2.0.0
running: /tmp/pear/temp/UI/configure --with-php-config=/usr/bin/php-config
checking for grep that handles long lines and -e... /bin/grep
checking for egrep... /bin/grep -E
checking for a sed that does not truncate output... /bin/sed
checking for cc... cc
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
checking for suffix of executables...
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether cc accepts -g... yes
checking for cc option to accept ISO C89... none needed
checking how to run the C preprocessor... cc -E
checking for icc... no
checking for suncc... no
checking whether cc understands -c and -o together... yes
checking for system library directory... lib
checking if compiler supports -R... no
checking if compiler supports -Wl,-rpath,... yes
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking target system type... x86_64-pc-linux-gnu
checking for PHP prefix... /usr
checking for PHP includes... -I/usr/include/php/20170718 -I/usr/include/php/20170718/main -I/usr/include/php/20170718/TSRM -I/usr/include/php/20170718/Zend -I/usr/include/php/20170718/ext -I/usr/include/php/20170718/ext/date/lib
checking for PHP extension directory... /usr/lib/php/20170718
checking for PHP installed headers prefix... /usr/include/php/20170718
checking if debug is enabled... no
checking if zts is enabled... no
checking for re2c... re2c
checking for re2c version... 1.0.1 (ok)
checking for gawk... no
checking for nawk... nawk
checking if nawk is broken... no
checking for ui support... yes, shared
checking for ui threads... no
checking for ui files in default path... found in /usr/local
checking for uiInit in -lui... yes
checking how to print strings... printf
checking for a sed that does not truncate output... (cached) /bin/sed
checking for fgrep... /bin/grep -F
checking for ld used by cc... /usr/bin/x86_64-linux-gnu-ld
checking if the linker (/usr/bin/x86_64-linux-gnu-ld) is GNU ld... yes
checking for BSD- or MS-compatible name lister (nm)... /usr/bin/nm -B
checking the name lister (/usr/bin/nm -B) interface... BSD nm
checking whether ln -s works... yes
checking the maximum length of command line arguments... 1572864
checking how to convert x86_64-pc-linux-gnu file names to x86_64-pc-linux-gnu format... func_convert_file_noop
checking how to convert x86_64-pc-linux-gnu file names to toolchain format... func_convert_file_noop
checking for /usr/bin/x86_64-linux-gnu-ld option to reload object files... -r
checking for objdump... objdump
checking how to recognize dependent libraries... pass_all
checking for dlltool... no
checking how to associate runtime and link libraries... printf %s\n
checking for ar... ar
checking for archiver @FILE support... @
checking for strip... strip
checking for ranlib... ranlib
checking for gawk... (cached) nawk
checking command to parse /usr/bin/nm -B output from cc object... ok
checking for sysroot... no
checking for a working dd... /bin/dd
checking how to truncate binary pipes... /bin/dd bs=4096 count=1
checking for mt... mt
checking if mt is a manifest tool... no
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking for dlfcn.h... yes
checking for objdir... .libs
checking if cc supports -fno-rtti -fno-exceptions... no
checking for cc option to produce PIC... -fPIC -DPIC
checking if cc PIC flag -fPIC -DPIC works... yes
checking if cc static flag -static works... yes
checking if cc supports -c -o file.o... yes
checking if cc supports -c -o file.o... (cached) yes
checking whether the cc linker (/usr/bin/x86_64-linux-gnu-ld -m elf_x86_64) supports shared libraries... yes
checking whether -lc should be explicitly linked in... no
checking dynamic linker characteristics... GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
checking if libtool supports shared libraries... yes
checking whether to build shared libraries... yes
checking whether to build static libraries... no
configure: creating ./config.status
config.status: creating config.h
config.status: executing libtool commands
running: make
/bin/bash /tmp/pear/temp/pear-build-root48Co5t/UI-2.0.0/libtool --mode=compile cc -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1 -I. -I/tmp/pear/temp/UI -DPHP_ATOM_INC -I/tmp/pear/temp/pear-build-root48Co5t/UI-2.0.0/include -I/tmp/pear/temp/pear-build-root48Co5t/UI-2.0.0/main -I/tmp/pear/temp/UI -I/usr/include/php/20170718 -I/usr/include/php/20170718/main -I/usr/include/php/20170718/TSRM -I/usr/include/php/20170718/Zend -I/usr/include/php/20170718/ext -I/usr/include/php/20170718/ext/date/lib -I/usr/local/include  -DHAVE_CONFIG_H  -g -O2   -c /tmp/pear/temp/UI/ui.c -o ui.lo
libtool: compile:  cc -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1 -I. -I/tmp/pear/temp/UI -DPHP_ATOM_INC -I/tmp/pear/temp/pear-build-root48Co5t/UI-2.0.0/include -I/tmp/pear/temp/pear-build-root48Co5t/UI-2.0.0/main -I/tmp/pear/temp/UI -I/usr/include/php/20170718 -I/usr/include/php/20170718/main -I/usr/include/php/20170718/TSRM -I/usr/include/php/20170718/Zend -I/usr/include/php/20170718/ext -I/usr/include/php/20170718/ext/date/lib -I/usr/local/include -DHAVE_CONFIG_H -g -O2 -c /tmp/pear/temp/UI/ui.c  -fPIC -DPIC -o .libs/ui.o
In file included from /tmp/pear/temp/UI/ui.c:76:0:
/tmp/pear/temp/UI/classes/descriptor.h:27:2: error: unknown type name ‘uiDrawTextFontDescriptor’
  uiDrawTextFontDescriptor d;
  ^~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/pear/temp/UI/ui.c:77:0:
/tmp/pear/temp/UI/classes/font.h:24:2: error: unknown type name ‘uiDrawTextFont’
  uiDrawTextFont* f;
  ^~~~~~~~~~~~~~
/tmp/pear/temp/UI/classes/font.h:25:2: error: unknown type name ‘uiDrawTextFontMetrics’
  uiDrawTextFontMetrics m;
  ^~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/php/20170718/main/php.h:40:0,
                 from /tmp/pear/temp/UI/ui.c:25:
/tmp/pear/temp/UI/ui.c: In function ‘zm_startup_ui’:
/usr/include/php/20170718/Zend/zend_API.h:131:45: warning: implicit declaration of function ‘zm_startup_UI_EditableCombo’; did you mean ‘zm_startup_UI_Ecombo’? [-Wimplicit-function-declaration]
 #define ZEND_MODULE_STARTUP_N(module)       zm_startup_##module
                                             ^
/usr/include/php/20170718/main/php.h:442:20: note: in expansion of macro ‘ZEND_MODULE_STARTUP_N’
 #define PHP_MINIT  ZEND_MODULE_STARTUP_N
                    ^~~~~~~~~~~~~~~~~~~~~
/tmp/pear/temp/UI/ui.c:151:2: note: in expansion of macro ‘PHP_MINIT’
  PHP_MINIT(UI_EditableCombo)(INIT_FUNC_ARGS_PASSTHRU);
  ^~~~~~~~~
/usr/include/php/20170718/Zend/zend_API.h:131:45: warning: implicit declaration of function ‘zm_startup_UI_MenuItem’; did you mean ‘zm_startup_UI_Item’? [-Wimplicit-function-declaration]
 #define ZEND_MODULE_STARTUP_N(module)       zm_startup_##module
                                             ^
/usr/include/php/20170718/main/php.h:442:20: note: in expansion of macro ‘ZEND_MODULE_STARTUP_N’
 #define PHP_MINIT  ZEND_MODULE_STARTUP_N
                    ^~~~~~~~~~~~~~~~~~~~~
/tmp/pear/temp/UI/ui.c:155:2: note: in expansion of macro ‘PHP_MINIT’
  PHP_MINIT(UI_MenuItem)(INIT_FUNC_ARGS_PASSTHRU);
  ^~~~~~~~~
/usr/include/php/20170718/Zend/zend_API.h:131:45: warning: implicit declaration of function ‘zm_startup_UI_DrawMatrix’; did you mean ‘zm_startup_UI_DrawPath’? [-Wimplicit-function-declaration]
 #define ZEND_MODULE_STARTUP_N(module)       zm_startup_##module
                                             ^
/usr/include/php/20170718/main/php.h:442:20: note: in expansion of macro ‘ZEND_MODULE_STARTUP_N’
 #define PHP_MINIT  ZEND_MODULE_STARTUP_N
                    ^~~~~~~~~~~~~~~~~~~~~
/tmp/pear/temp/UI/ui.c:163:2: note: in expansion of macro ‘PHP_MINIT’
  PHP_MINIT(UI_DrawMatrix)(INIT_FUNC_ARGS_PASSTHRU);
  ^~~~~~~~~
/tmp/pear/temp/UI/ui.c:169:2: warning: implicit declaration of function ‘php_ui_control_finalize’; did you mean ‘php_ui_control_fetch’? [-Wimplicit-function-declaration]
  php_ui_control_finalize();
  ^~~~~~~~~~~~~~~~~~~~~~~
  php_ui_control_fetch
/tmp/pear/temp/UI/ui.c: In function ‘zif_fontFamilies’:
/tmp/pear/temp/UI/ui.c:320:2: error: unknown type name ‘uiDrawFontFamilies’; did you mean ‘uiDrawTextAlign’?
  uiDrawFontFamilies* families;
  ^~~~~~~~~~~~~~~~~~
  uiDrawTextAlign
/tmp/pear/temp/UI/ui.c:329:13: warning: implicit declaration of function ‘uiDrawListFontFamilies’; did you mean ‘zif_fontFamilies’? [-Wimplicit-function-declaration]
  families = uiDrawListFontFamilies();
             ^~~~~~~~~~~~~~~~~~~~~~
             zif_fontFamilies
/tmp/pear/temp/UI/ui.c:329:11: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
  families = uiDrawListFontFamilies();
           ^
/tmp/pear/temp/UI/ui.c:330:30: warning: implicit declaration of function ‘uiDrawFontFamiliesNumFamilies’ [-Wimplicit-function-declaration]
  for (familiy = 0; familiy < uiDrawFontFamiliesNumFamilies(families); familiy++) {
                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/tmp/pear/temp/UI/ui.c:331:39: warning: implicit declaration of function ‘uiDrawFontFamiliesFamily’; did you mean ‘zif_fontFamilies’? [-Wimplicit-function-declaration]
   add_next_index_string(return_value, uiDrawFontFamiliesFamily(families, familiy));
                                       ^~~~~~~~~~~~~~~~~~~~~~~~
                                       zif_fontFamilies
/tmp/pear/temp/UI/ui.c:331:39: warning: passing argument 2 of ‘add_next_index_string’ makes pointer from integer without a cast [-Wint-conversion]
In file included from /usr/include/php/20170718/main/php.h:40:0,
                 from /tmp/pear/temp/UI/ui.c:25:
/usr/include/php/20170718/Zend/zend_API.h:450:14: note: expected ‘const char *’ but argument is of type ‘int’
 ZEND_API int add_next_index_string(zval *arg, const char *str);
              ^~~~~~~~~~~~~~~~~~~~~
/tmp/pear/temp/UI/ui.c:334:2: warning: implicit declaration of function ‘uiDrawFreeFontFamilies’; did you mean ‘zif_fontFamilies’? [-Wimplicit-function-declaration]
  uiDrawFreeFontFamilies(families);
  ^~~~~~~~~~~~~~~~~~~~~~
  zif_fontFamilies
Makefile:195: recipe for target 'ui.lo' failed
make: *** [ui.lo] Error 1
ERROR: `make' failed

class UI\Control
{
	protected $on = [];

	protected function on(string $event, callable $callback): self
	{
		if (!($callback instanceof \Closure)) {
			$callback = \Closure::fromCallable($callback);
		}
		$this->on[strtolower($event)] = $callback;
		return $this;
	}
}

class UI\Controls\Button extends UI\Control
{
	public function onClick(callable $callback): self
	{
		return $this->on('click', $callback);
	}
}