Combobox MaxDropDownHeight has no effect if IsEditable is set to true

[bogdan-patraucean]

Describe the bug

I can't set the maximum number of items displayed by the combobox dropdown if IsEditable is set to true.

<ComboBox MaxDropDownHeight="400"  IsEditable="True">
     <x:String>Item 1</x:String>
     <x:String>Item 2</x:String>
     <x:String>Item 3</x:String>
     <x:String>Item 4</x:String>
     <x:String>Item 5</x:String>
     <x:String>Item 6</x:String>
     <x:String>Item 7</x:String>
     <x:String>Item 8</x:String>
     <x:String>Item 9</x:String>
     <x:String>Item 10</x:String>
     <x:String>Item 11</x:String>
     <x:String>Item 12</x:String>
     <x:String>Item 13</x:String>
     <x:String>Item 14</x:String>
     <x:String>Item 15</x:String>
 </ComboBox>

MaxDropDownHeight of 400 would display 10 items. I even tried overriding the keyed resource but this still does not work:

<x:Int32 x:Key="ComboBoxPopupMaxNumberOfItems">15</x:Int32> 

Why is this important?

It's important because sometimes, on some screen sizes, 15 items is too much. The fact that the behaviour is inconsistent, in the sense that IsEditable = False will work, makes the combobox an incomplete control.

Steps to reproduce the bug

Just add a combobox with the snippet above.

Actual behavior

MaxDropDownHeight has no effect.

Expected behavior

MaxDropDownHeight should have effect.

Screenshots

No response

NuGet package version

WinUI 3 - Windows App SDK 1.8.2: 1.8.251003001

Windows version

Windows 11 (24H2): Build 26100

Additional context

No response