feat(controls): Add `TitleBar` CenterContent property #1484

luca-domenichini · 2025-07-11T14:32:16Z

This PR is fix for #1483
It adds a CenterContent DependencyProperty and a new column in the Grid of TitleBar, making developer able to put content in the center area of the titlebar.

Moreover, with HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" we make developer able to align the centered area more precisely, to the left, center or right edge.

Pull request type

Please check the type of change your PR introduces:

What is the current behavior?

Currently there are few, less obvious alternatives.

Issue Number: #1483

What is the new behavior?

Devs are now able to put content directly in the centered area of the title bar.

… TitleBar

minimizing changes

…leBar

Merge 2025-11-12 from base repo

Copilot

Pull Request Overview

This PR adds a CenterContent property to the TitleBar control, enabling developers to place content in the center area of the title bar.

Key changes:

New CenterContent dependency property with getter/setter
Updated XAML template with additional grid column for centered content
Enhanced mouse hit-testing logic to handle center content interactions

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/Wpf.Ui/Controls/TitleBar/TitleBar.cs	Added `CenterContent` dependency property and updated window procedure hook to handle mouse-over detection for center content
src/Wpf.Ui/Controls/TitleBar/TitleBar.xaml	Added new grid column and ContentPresenter for center content, reordered existing columns

Copilot · 2025-11-12T14:59:09Z

src/Wpf.Ui/Controls/TitleBar/TitleBar.cs

+		if (message == PInvoke.WM_NCHITTEST)
+		{
+			if (TrailingContent is UIElement || Header is UIElement || CenterContent is UIElement)
+			{
+				UIElement? headerLeftUIElement = Header as UIElement;
+				UIElement? headerCenterUIElement = CenterContent as UIElement;
+				UIElement? headerRightUiElement = TrailingContent as UIElement;

-        var e = new HwndProcEventArgs(hwnd, msg, wParam, lParam, isMouseOverHeaderContent);
-        WndProcInvoked?.Invoke(this, e);
+				isMouseOverHeaderContent = (headerLeftUIElement is not null && headerLeftUIElement != _titleBlock && headerLeftUIElement.IsMouseOverElement(lParam))
+					|| (headerCenterUIElement?.IsMouseOverElement(lParam) ?? false)
+					|| (headerRightUiElement?.IsMouseOverElement(lParam) ?? false);
+			}

-        if (e.ReturnValue != null)
-        {
-            handled = e.Handled;
-            return e.ReturnValue ?? IntPtr.Zero;
-        }
+			htResult = GetWindowBorderHitTestResult(hwnd, lParam);
+		}


Tabs are used for indentation instead of spaces. According to the project's .editorconfig, C# files should use spaces (indent_style = space). Please replace tabs with spaces for consistent formatting.

Copilot · 2025-11-12T14:59:10Z

src/Wpf.Ui/Controls/TitleBar/TitleBar.cs

+		}

-        switch (message)
+		switch (message)


Tab used for indentation instead of spaces. According to the project's .editorconfig, C# files should use spaces (indent_style = space). Please replace the tab with spaces.

Suggested change

switch (message)

switch (message)

Copilot

Pull Request Overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

src/Wpf.Ui/Controls/TitleBar/TitleBar.cs

luca-domenichini · 2025-12-09T15:39:48Z

Hi @pomianowski , is there something more I can do to make this PR go ahead?
Maybe I could ask for @Nuklon review, since I see he is probably the most active dev on this repo?

apachezy · 2025-12-16T08:20:11Z

I had also used the same approach to allow user content in the center of the title bar, but I realized it might be a temporary workaround and didn't submit a PR.

Later, I found that changing the HorizontalAlignment of the TrailingContent to Stretch would allow users to freely place content (left, center, or right), because:

<Grid.ColumnDefinitions>
    <ColumnDefinition Width="Auto" /> <!-- Title text or other header content -->
    <ColumnDefinition Width="*" /> <!-- TrailingContent!!!!!!!!!!! -->
    <ColumnDefinition Width="Auto" /> <!-- System buttons -->
</Grid.ColumnDefinitions>

The column where TrailingContent resides has a width of "*", but its HorizontalAlignment was set to Right. This is not reasonable — even though the remaining space is fully available, users were forced to align their content to the "right".

Changing it to Stretch is both logical and user-friendly, as it allows content to utilize the full available space. Why not do it?

Moreover, this method requires minimal changes, especially since no modifications are needed in the HwndSourceHook. This also means minimal burden for reviewers.

Back then, I wasn't very familiar with the PR process. I once accidentally included this change in a PR, but it was rejected — haha!

luca-domenichini · 2025-12-16T08:34:02Z

I think your arguments are valuable. Thanks for adding your point of view ⭐ Let's hope for a review by the maintainers! ⭐

luca-domenichini · 2025-12-16T08:35:41Z

@apachezy thumb up the PR if you want to push it further 👍

apachezy · 2025-12-16T08:39:53Z

So I suggest adopting the "TrailingContent.HorizontalAlignment = Stretch" approach, mark the TrailingContent property as obsolete, introduce a new property (e.g., "RemainingSpaceContent") to replace it, and then internally link TrailingContent to this new property.

This way, the changes required are minimal. It avoids cluttering TitleBar with too many "Content" properties, while still meeting the requirements. Why not go for it?

apachezy · 2025-12-16T08:41:51Z

I'll wait for your new solution to be implemented, and I'll give you a ton of likes for it! 👍

luca-domenichini · 2025-12-16T08:50:47Z

hmm.. I think having just a new center property will not break existing applications. Changing the existing one as you suggest, also could break them.
My PR just add new content where previously there was nothing, so existing stuff should still work.
If we change the existing to Stretch I fear many users would be affected.. am I wrong?

apachezy · 2025-12-16T09:00:26Z

Hmm... I think this is just part of the natural process of software iteration. Changing the TrailingContent.HorizontalAlignment property would only have the effect of making content that was originally right-aligned appear "distributed". Once developers notice this, they'll realize: "Haha, now I can place content anywhere I want!"

luca-domenichini · 2025-12-16T09:13:10Z

I see your point, for a brand new library would make more sense, and yes, for me would not be a problem since I'm making the PR and I would naturally adapt my code as well.

Though, I think the kind of change you are suggesting should be approved by maintainers more carefully, and since I want this PR to go fast without breaking anyone.. well.. let's wait for @pomianowski to react to your points.

Repeating myself: for me would be OK with your proposal. Just curious about owner directions.

apachezy · 2025-12-16T09:21:03Z

I feel that there are still some unresolved concerns in the current TitleBar implementation, particularly regarding the combination of WPF techniques and the Windows message–based approach.

While it seems to be working correctly right now, this is largely thanks to the accumulated efforts of multiple contributors.

I expect that more focused refinements will be needed in the future, so at this stage, I think it makes sense to achieve the required functionality with minimal changes.

luca-domenichini and others added 2 commits July 11, 2025 13:00

ADD TitleBar CenterContent property to allow content in the middle of…

93661a4

… TitleBar

Update TitleBar.cs

04f1c13

minimizing changes

luca-domenichini requested a review from pomianowski as a code owner July 11, 2025 14:32

github-actions bot added controls Changes to the appearance or logic of custom controls. styles Topic is related to styles PR Pull request dotnet release titlebar Titlebar updates labels Jul 11, 2025

luca-domenichini added 2 commits July 15, 2025 22:25

bind center area VerticalAlignment to VerticalContentAlignment of Tit…

41e575d

…leBar

Merge branch 'main' of https://github.com/luca-domenichini/wpfui

821e785

This was referenced Jul 15, 2025

Titlebar - cannot add custom button #1301

Open

The Title and Icon of the TitleBar cannot be centered horizontally #1490

Open

github-actions bot added the ⭐ top pull request Top pull request. label Jul 24, 2025

github-actions bot mentioned this pull request Jul 24, 2025

Top Issues Dashboard #1288

Open

pomianowski linked an issue Nov 7, 2025 that may be closed by this pull request

TitleBar - ADD support for a centered content area #1483

Open

pomianowski changed the title ~~ADD TitleBar CenterContent property, fix for #1483~~ feat(controls): Add TitleBar CenterContent property Nov 7, 2025

luca-domenichini and others added 2 commits November 12, 2025 15:54

Merge from main

ca36d66

Merge pull request #2 from luca-domenichini/merge-2025-11-12

6366d69

Merge 2025-11-12 from base repo

Copilot AI review requested due to automatic review settings November 12, 2025 14:55

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luca-domenichini added 2 commits November 12, 2025 16:03

Restored missing statements

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untabify

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Fix formatting in TitleBar.cs

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luca-domenichini added 2 commits November 24, 2025 11:45

Merge branch 'lepoco:main' into main

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Merge branch 'main' into main

cf04daf

Merge branch 'main' into main

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feat(controls): Add `TitleBar` CenterContent property #1484

feat(controls): Add `TitleBar` CenterContent property #1484

luca-domenichini commented Jul 11, 2025 •

edited by pomianowski

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