为什么NSWindow没有styleMask：NSTitledWindowMask不能是keyWindow？

问题描述

问题：
我有一个窗口mainWindow，另一个 childWindow 添加到 mainWindow 。
childWindow是一种 WindowExt 类。这个类定义为catch方法调用 [NSWindow becomeKeyWindow] ，必须在 [childWindow makeKeyWindow] 后调用。
如果我创建childWindow并试图让它在下一个keyWindow：

  WindowExt * childWindow = [[WindowExt alloc ] initWithContentRect：addedWindowRect 
 styleMask：NSBorderlessWindowMask | NSTitledWindowMask 
 backing：NSBackingStoreBuffered 
 defer：NO]; 
 [mainWindow addChildWindow：childWindow ordered：NSWindowAbove]; 
 [childWindow makeKeyWindow]; 
  

方法 [WindowExt becomeKeyWindow] c $ c> childWindow 被调用 - 一切正常， childWindow 成为keyWindow。

但是如果我创建childWindow作为

  WindowExt * childWindow = [[WindowExt alloc] initWithContentRect：addedWindowRect 
 styleMask：NSBorderlessWindowMask 
 backing：NSBackingStoreBuffered 
 defer：NO]; 
 [mainWindow addChildWindow：childWindow ordered：NSWindowAbove]; 
 [childWindow makeKeyWindow]; 
  

不含 NSTitledWindowMask ，，childWindow 不会被调用 - childWindow 不会成为keyWindow 。

解决方案

这是Cocoa设计决策：。 p>

如果你想要一个无标题窗口能够成为一个关键窗口，你需要创建一个 NSWindow 重写 -canBecomeKeyWindow 如下：

   - （BOOL）canBecomeKeyWindow {
 return YES; 
} 
  

Problem:I have one window mainWindow and another childWindow added to mainWindow.childWindow is kind of WindowExt class. This class I define for catch method call [NSWindow becomeKeyWindow] that must be called after [childWindow makeKeyWindow].If I create childWindow and try to make it keyWindow on next way:

WindowExt *childWindow = [[WindowExt alloc] initWithContentRect:addedWindowRect
                           styleMask:NSBorderlessWindowMask | NSTitledWindowMask
                             backing:NSBackingStoreBuffered 
                               defer:NO];
[mainWindow addChildWindow:childWindow ordered:NSWindowAbove];
[childWindow makeKeyWindow];

method [WindowExt becomeKeyWindow] for childWindow is called - all fine, childWindowbecome keyWindow.

But if I create childWindow as

WindowExt *childWindow = [[WindowExt alloc] initWithContentRect:addedWindowRect
styleMask:NSBorderlessWindowMask 
backing:NSBackingStoreBuffered
defer:NO];
[mainWindow addChildWindow:childWindow ordered:NSWindowAbove];
[childWindow makeKeyWindow];

without NSTitledWindowMask, [WindowExt becomeKeyWindow] for childWindow is never called - childWindow doesn't become keyWindow.

解决方案

That’s a Cocoa design decision: windows without title or resize bar cannot become key window by default.

If you want a titleless window to be able to become a key window, you need to create a subclass of NSWindow and override -canBecomeKeyWindow as follows:

- (BOOL)canBecomeKeyWindow {
    return YES;
}

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