fix(DoubleUpDown): revert to previous value on out-of-range input with ClipValueToMinMax=false (fixes #1801)

[JyslaFancy]

Fixes #1801 — DoubleUpDown with ClipValueToMinMax=false silently truncates digits instead of reverting.

Problem

When ClipValueToMinMax=false and user enters an out-of-range value then tabs away (UpdateSourceTrigger=LostFocus), the control silently truncates digits. For example with Max=20000, typing 123456 sets the VM property to 12345.

Root cause

Intermediate valid values (e.g. 12345) were committed to the internal Value property during typing via SyncTextAndValueProperties. On LostFocus, when the final value was out of range, the catch block raised a validation error but the display text was reverted to the last committed intermediate value.

Fix

1. Added _initialValueOnFocus field to save the Value when focus is gained
2. In UpDownBase_IsKeyboardFocusWithinChanged, save this.Value on focus gain
3. In the SyncTextAndValueProperties catch block, when !_isTextChangedFromUI and !ClipValueToMinMax, restore _initialValueOnFocus via SetValueInternal before raising the validation error

This ensures the control reverts to the correct pre-edit value instead of a truncated intermediate value.

[robertovargash]

Fixes #1801 — DoubleUpDown with ClipValueToMinMax=false silently truncates digits instead of reverting.

Problem

When ClipValueToMinMax=false and user enters an out-of-range value then tabs away (UpdateSourceTrigger=LostFocus), the control silently truncates digits. For example with Max=20000, typing 123456 sets the VM property to 12345.

Root cause

Intermediate valid values (e.g. 12345) were committed to the internal Value property during typing via SyncTextAndValueProperties. On LostFocus, when the final value was out of range, the catch block raised a validation error but the display text was reverted to the last committed intermediate value.

Fix

1. Added _initialValueOnFocus field to save the Value when focus is gained
2. In UpDownBase_IsKeyboardFocusWithinChanged, save this.Value on focus gain
3. In the SyncTextAndValueProperties catch block, when !_isTextChangedFromUI and !ClipValueToMinMax, restore _initialValueOnFocus via SetValueInternal before raising the validation error

This ensures the control reverts to the correct pre-edit value instead of a truncated intermediate value.

Thanks for the report and the fix in #1801 — we merged it into UpDownBase.

Your diagnosis was right: partial values like 12345 were sticking around on focus loss instead of rolling back to the value before the edit.

We kept your approach and added a couple of small things on our side so the bound property also updates correctly with UpdateSourceTrigger=LostFocus.

Appreciate you taking the time to document this.