dotnet/wpf · error · ArgumentException

Microsoft.Windows.Controls.SR.InvalidKeyTipOffset

Error message

Microsoft.Windows.Controls.SR.InvalidKeyTipOffset

What it means

ActivatingKeyTipEventArgs.HorizontalOffset validates its value: the key tip offset must be a finite number. Setting it to double.PositiveInfinity, double.NegativeInfinity, or double.NaN throws ArgumentException with SR.InvalidKeyTipOffset, because the KeyTipService cannot position the key tip with a non-finite offset.

Solutions

Validate the computed offset with double.IsFinite before assigning it to HorizontalOffset
Fix the upstream calculation producing Infinity/NaN (e.g. guard division by zero, check layout size of 0)
Clamp the offset to a sane fallback value (e.g. 0) when the computation fails
Catch ArgumentException in the key tip handler and substitute a default offset

Example fix

// before
e.HorizontalOffset = desiredWidth / itemCount; // NaN/Infinity when itemCount == 0
// after
double offset = itemCount > 0 ? desiredWidth / itemCount : 0;
e.HorizontalOffset = double.IsFinite(offset) ? offset : 0;

Defensive patterns

Strategy: validation

Validate before calling

if (!double.IsFinite(offset)) offset = 0;
e.HorizontalOffset = offset;

Type guard

bool IsValidKeyTipOffset(double v) => !double.IsInfinity(v) && !double.IsNaN(v);

Try / catch

try { e.HorizontalOffset = computedOffset; }
catch (ArgumentException) { e.HorizontalOffset = 0; }

Prevention

Run double.IsFinite on all computed offsets before assignment
Guard divisions used in key tip position math
Verify layout has completed before computing screen coordinates
Clamp out-of-range layout results to safe defaults

When it happens

Trigger: In a KeyTipActivating / ActivatingKeyTipEventArgs handler (or code computing the offset), assigning HorizontalOffset a value that is Infinity or NaN — often from a division by zero or an unset computed position.

Common situations: Custom key tip positioning logic computing offsets from layout math that divides by zero; uninitialized double fields defaulting and later propagating NaN through calculations.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/1e93a38b3c3601b4. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/System.Windows.Controls.Ribbon/Microsoft/Windows/Controls/ActivatingKeyTipEventArgs.cs:86

        {
            get;
            set;
        }

        /// <summary>
        ///     Horizontal offset from the defined horizontal placement.
        /// </summary>
        public double KeyTipHorizontalOffset
        {
            get
            {
                return _horizontalOffset;
            }
            set
            {
                if (double.IsInfinity(value) || double.IsNaN(value))
                {
                    throw new ArgumentException(Microsoft.Windows.Controls.SR.InvalidKeyTipOffset);
                }
                _horizontalOffset = value;
            }
        }

        /// <summary>
        ///     Vertical offset from the defined vertical placement.
        /// </summary>
        public double KeyTipVerticalOffset
        {
            get
            {
                return _verticalOffset;
            }
            set
            {
                if (double.IsInfinity(value) || double.IsNaN(value))
                {

View on GitHub (pinned to 81131a70a4)