Form.Text does not update

I have this one window where when I set the Text property of the Form it does not update the title bar. I am 100% sure my code is being called and the Text value is being changed. It's just not physically painting it on the screen.

I have about 100 or so Forms and this is the only Form that does this. I've compared properties with a window that does work and can't see anything odd that I'm doing in the broken Form. Has anyone run accross this or have an idea of things I can check?

How are you updating the value; could you post some of your code?

• Is the .Text property being set on the same thread that instantiated the form?
• Set a breakpoint to make sure it's been hit
• Make a copy of your form's code and reduce it down until you get the smallest amount of code that reproduces the problem, then compare it to a working sample.

W3bbo said:

• Is the .Text property being set on the same thread that instantiated the form?
• Set a breakpoint to make sure it's been hit
• Make a copy of your form's code and reduce it down until you get the smallest amount of code that reproduces the problem, then compare it to a working sample.

I can't seem to find a different between the windows.

I have a method called UpdateTitle() that actually updates the Form's Text. InvokeRequired always returns false, so it's definately not in the wrong Thread. Nothing related to this window is multi-threaded so this was not surprising.

When I put in a breakpoint, the title does update. I suspect that's because Visual Studio takes focus and when I go back to the window, it triggers a re-paint of the non-client area. The title change also shows up if I minimize, then maximize the window.

ploe said:

W3bbo said:

*snip*

I can't seem to find a different between the windows.

 

I have a method called UpdateTitle() that actually updates the Form's Text. InvokeRequired always returns false, so it's definately not in the wrong Thread. Nothing related to this window is multi-threaded so this was not surprising.

 

When I put in a breakpoint, the title does update. I suspect that's because Visual Studio takes focus and when I go back to the window, it triggers a re-paint of the non-client area. The title change also shows up if I minimize, then maximize the window.

Can you post your code?

W3bbo said:

ploe said:

*snip*

Can you post your code?

I'm an idiot. I couldn't find the bug because it wasn't in the window's code, but our base class that it extends. The other windows where the title update does work inherits a different base class.

In our base class we disabled painting while the window was in a state of populating data (because we were getting flicker) with this line:

SendMessage(this.Handle, WM_SETREDRAW, 0, IntPtr.Zero);

We re-enabled painting when it is done populating with this line:

SendMessage(this.Handle, WM_SETREDRAW, 1, IntPtr.Zero);

Then we call Invalidate(true). But that just invalidates the client area, not the non-client area, hence why the title bar was not re-painting.

Solution:

Invalidate and paint the ENTIRE window by calling: InvalidateRect() and then UpdateWindow().

Sorry for the wild goose chase.

ploe said:

W3bbo said:

*snip*

I'm an idiot. I couldn't find the bug because it wasn't in the window's code, but our base class that it extends. The other windows where the title update does work inherits a different base class.

 

In our base class we disabled painting while the window was in a state of populating data (because we were getting flicker) with this line:

SendMessage(this.Handle, WM_SETREDRAW, 0, IntPtr.Zero);

 

We re-enabled painting when it is done populating with this line:

SendMessage(this.Handle, WM_SETREDRAW, 1, IntPtr.Zero);

 

Then we call Invalidate(true). But that just invalidates the client area, not the non-client area, hence why the title bar was not re-painting.

 

Solution:

Invalidate and paint the ENTIRE window by calling: InvalidateRect() and then UpdateWindow().

 

Sorry for the wild goose chase.

If you're getting flickering just enable double-buffering. Disabling painting whilst populating just feels like a bad move.