CommandTip

CommandTip

The Command Tip: the themed tooltip the Command Bar — and the editor's other command buttons — shows on hover. In place of a bare one-line hint it names the action and explains it: the action's Name as a heading, a short line saying what the action does, and, when the action has one, its key gesture as a small chip.

• Class: UI.Controls.CommandTip (derives from System.Windows.Controls.ToolTip)
• Default style: Controls/CommandTip.xaml, merged in App.xaml
• Used by: every command button, dropdown header, and dropdown entry in MainWindow.xaml

Authored as a custom Control — a ToolTip subclass plus a ResourceDictionary for its look — per the project's Control exception to the zero-code-behind rule. It is presentation-only: a Command Tip names and explains an action, it never performs one.

Why a custom control

WPF's stock ToolTip is a pale, system-drawn popup that ignores the palette; in the dark theme it reads as a glaring near-white box — the same bug the stock TextBox and ComboBox carry, which Themes/Controls.xaml fixes with implicit styles. Deriving from ToolTip lets a Command Tip do two things at once:

• carry structured content — a heading, a detail line, and an optional gesture, rather than one flat string; and
• paint itself from the active palette — every color in its template is a DynamicResource lookup, so a theme swap recolors it live.

Because a CommandTip is a ToolTip, it is assigned straight to an element's ToolTip and shown with its own template — no stock tooltip is wrapped around it. The plain-string tooltips that remain (the Editor Gutter's Fold Toggle, the Diagram Builder's connector handle) are themed by the sibling implicit ToolTip style in Themes/Controls.xaml.

Properties

Property	Type	Description
Heading	string	The action's Name — what it is (e.g. "Bold"). Shown as the tip's heading. Defaults to empty.
Detail	string	A short, plain-language line on what the action does. Shown beneath the heading; collapses when empty. Defaults to empty.
Gesture	string	The action's key gesture (e.g. "Ctrl+B"), shown as a chip beside the heading. Collapses when empty, for actions with no gesture. Defaults to empty.

All three default to the empty string (never null), so the template's "collapse when empty" triggers fire on a plain string comparison and an unfilled tip shows nothing where a missing piece would be.

Usage

Set one as the element's tooltip and fill in the three properties:

<Button Style="{StaticResource IconFormatButton}"
        Command="EditingCommands.ToggleBold" CommandTarget="{Binding ElementName=Editor}"
        AutomationProperties.Name="Bold">
    <Button.ToolTip>
        <controls:CommandTip Heading="Bold"
                             Detail="Make the selected text bold, or turn bold text back to normal."
                             Gesture="Ctrl+B" />
    </Button.ToolTip>
    <Path Style="{StaticResource CommandIcon}" Data="{StaticResource Icon.ToggleBold}" />
</Button>

Heading mirrors the button's AutomationProperties.Name (what a screen reader reads), so the action is named the same way to a sighted user hovering and to an assistive-technology user.

Showing while disabled

By default WPF hides a control's tooltip once the control is disabled — but a greyed-out command is exactly when the user most wants to know what it is and why it is unavailable. So the shared command styles in Themes/Controls.xaml — CommandButton (the base for every command button), CommandMenuItem (a dropdown header), and CommandMenuEntry (a dropdown entry) — set:

<Setter Property="ToolTipService.ShowOnDisabled" Value="True" />

ShowOnDisabled belongs on the hovered element, not on the tooltip, so it lives in these styles rather than in CommandTip. Every command button, dropdown, and dropdown entry derives from one of them, so all of them show their Command Tip whether enabled or not.

Tests

• CommandTipTests — the control is a ToolTip, and its three properties round-trip and default to empty.
• CommandTipStyleTests — the CommandTip default style and the implicit ToolTip style are defined, target the right types, and take every color from the palette (no literal a theme swap could not recolor); and the shared command styles set ToolTipService.ShowOnDisabled so a disabled command still shows its tip.