问题

I created a TForm in the IDE of C++Builder with BorderStyle=bsDialog and made it available following this tutorial:

Dynamically Creating a VCL Modal Form.

I then POST a custom message in the MainForm::OnShow() event, which then sets a FireDAC connection to true which has the LoginPrompt property enabled and uses the OnLogin() event, which then opens up my form.

My issue is that my TEdit field does not get the focus when the dialog is opened. The form contains a TImage using an icon, a TGradientLabel, a TEdit, a TStaticText, and two TButtons for Ok (default) and Cancel. When the form is first opened, pressing Tab makes the focus go to the Ok button, but without the dashed line to indicate input focus; using Shift-Tab goes to the Cancel button, but without the dashed line to indicate input focus. After pressing Tab or Shift-Tab, the next Tab or Shift-Tab works and has the dashed line (when on a button). When the form is first opened, if you Tab then Shift-Tab, or Shift-Tab then Tab, the TEdit field has the cursor and input like it should have from the start.

Here's basically how I set up / start the form:

MyForm=new TMyForm(MainForm);
MyForm->ActiveControl=MyForm->EditName;
MyForm->ShowModal();
MyForm->Free();

I found that if I click another Window then click back to my Main Window (or even if I just click on itself on the Taskbar), it also works, and the TEdit control has the cursor.

I even tried setting up an event for OnShow for the dialog and used ::SetForegroundWindow(), ::SetActiveWindow() for the Form, and tried again setting ActiveControl, and even using MyForm->SetFocus(), but nothing is working.

I'm using Windows 10, is there something else that needs to be done (clearly there is)?

MyForm=new TMyForm(MainForm);
MyForm->ActiveControl=MyForm->EditName;
MyForm->ShowModal();
MyForm->Free();

答案1

得分: 3

无需手动将焦点设置到您的 TEdit 控件，如果您已经正确设计了您的表单对话框。

在设计时，您可以通过设置它们的 TabOrder 属性来控制可接受焦点组件的访问顺序。

默认情况下，表单设计器根据您已经放置在表单上的组件的顺序设置 TabOrder 属性。例如，如果您先放置了两个按钮，然后放置编辑控件，它的 TabOrder 将设置为 2。

因此，要解决您的问题，您只需简单地将 TEdit 组件的 TabOrder 属性更改为 0，这将确保在显示表单时它获得焦点。

如果您有多个 TEdit 控件（用户名和密码），请将用户名编辑的 TabOrder 属性设置为 0，将密码编辑的 TabOrder 属性设置为 1。这样，用户可以使用 Tab 键从用户名移动到密码控件。

答案2

得分: -2

我对内部情况的细节不太确定（不确定如何让spy++在窗口存在之前监视窗口的消息），但我通过简单地多次重试自定义消息（`UWM_MAINDIALOGSHOWN`）来解决了这个问题，我发现即使一次也足够了。我将这个放在我的自定义消息的顶部：

```c++
static int redo=1;
if (redo) {
	redo--;
	PostMessage(Handle, UWM_MAINDIALOGSHOWN, 0, 0);
	return;
}

如果有人对内部情况有更多细节，那将是很棒的，但至少现在有一些可以解决这个问题的方法。

<details>
<summary>英文:</summary>

I&#39;m not sure of the details of what is going on internally (not sure how to get spy++ to watch the messages of a Window before the Window exist), but I solved the issue by simply retrying the custom message (`UWM_MAINDIALOGSHOWN`) again multiple times, I got it down that even 1 time is enough.  I put this at the top of my custom message:

```c++
static int redo=1;
if (redo) {
	redo--;
	PostMessage(Handle, UWM_MAINDIALOGSHOWN, 0, 0);
	return;
}

If someone has more details on the internals, that be great, but at least there is something that works if someone else runs in to this.