Demonstrate making a Wpf Frame control's Arrows enlarging

FixArrowSizes.cs

using System.Windows;
using System.Windows.Controls;
void Main()
{
	var w = new Window();
	var grid = new Grid();
//	Func<FrameworkElement,UIElement> getTemplateChild = x => {
//		var flags = BindingFlags.NonPublic | BindingFlags.Instance
//		var tcm = x.GetType().GetMember("get_TemplateChild", flags)[0] as MethodInfo;
//		var result = tcm.Invoke(x,null);
//		return result as UIElement;
//	};
	
	grid.RowDefinitions.Add(new RowDefinition(){MinHeight=80,Height=new GridLength(80)});
	grid.RowDefinitions.Add(new RowDefinition(){Height=new GridLength(200)});
	grid.RowDefinitions.Add(new RowDefinition(){Height=new GridLength(200)});
	grid.Children.Add(GenerateDemoFrame(1));
	var frame2 = GenerateDemoFrame(2);
	grid.Children.Add(frame2);
	w.Content = grid;
	
	
	w.Dump();
	FixArrowSize(frame2);
}

static Frame GenerateDemoFrame(int gridRow) {
	var f = new Frame();
	f.NavigationUIVisibility = System.Windows.Navigation.NavigationUIVisibility.Visible;
	var page = new Page() { Content = new Button() { Content = $"Hello from row {gridRow + 1} (index {gridRow})"}};
	f.Navigate(page);
	f.SetValue(Grid.RowProperty,gridRow);
	return f;
}

static UIElement GetTemplateChild(FrameworkElement x)
{
	var flags = System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance;
	var tcm = x.GetType().GetMember("get_TemplateChild", flags)[0] as System.Reflection.MethodInfo;
	var result = tcm.Invoke(x, null);
	return result as UIElement;
}

// Define other methods and classes here
static DockPanel GetDockPanel(FrameworkElement sender)
{
	var child = GetTemplateChild(sender);
	// if the frame has been drawn/nav enabled, child will be a border first
	if (child is Border b)
	{
		child = b.Child;
	}
	var dp = child as DockPanel;
	return dp;
}


static void FixArrowSize(Frame frame)
{
	var dp = GetDockPanel(frame);
	if (dp is null)
		return;
	var grid = dp.Children.OfType<Grid>().FirstOrDefault();
	var path = grid.Children.OfType<System.Windows.Shapes.Path>().FirstOrDefault();
	// we did it, we're going to be called multiple times, but only need to do our job once
	if (path == null)
		return;
	grid.Children.Remove(path);
	var size = 40.0;

	grid.Children.OfType<Control>().ToList().ForEach(c =>
	{
		c.MinHeight = size;
		c.MinWidth = size;
		if (c is Button b)
		{
			var content = b.Content;
			var child = GetTemplateChild(b) as Grid;
			child.MinHeight = size;
			child.MinWidth = size;
					//} else if(c is Menu m)
					//{
					//    var content = GetTemplateChild(m) as FrameworkElement;
					//    content.MinHeight = size;
					//    content.MinWidth = size;
				}
	});
	var cd = grid.ColumnDefinitions;
	cd[0].Width = new GridLength(size);
	cd[1].Width = new GridLength(size);
	// no row definitions
	var rd = grid.RowDefinitions;
	grid.MinHeight = size;
	// see if you can see the current height/width of the column/rows and adjust the definitions, see if that changes the size
	//frame

}

FixArrowSizes.fs

// 
open 
module Option =
    let inline ofCast<'t> (x:obj) =
        match x with
        | :? 't as v -> Some v
        | _ -> None
module Seq =
    let inline ofType<'t> (items:_ seq) =
        items |> Seq.choose(box >> Option.ofCast<'t>)
module WpfHelpers =
    open System.Reflection
    let getChildren (x:Panel) =
        x.Children
    let getChildrenOfType<'t> (x:Panel) : 't seq =
        x
        |> getChildren
        |> Seq.cast<obj>
        |> Seq.ofType<'t>
    let getTemplateChild(x :FrameworkElement) =
        let flags = BindingFlags.NonPublic ||| BindingFlags.Instance
        let tcm = x.GetType().GetMember("get_TemplateChild", flags).[0] :?> MethodInfo
        let result = tcm.Invoke(x,null)
        result :?> UIElement
        
    let getDockPanel (sender:FrameworkElement) =
        // if the frame has been drawn/nav enabled, child will be a border first
        let rec tryDP tryAgain (x:UIElement):DockPanel=
            match x with
            | :? Border as b ->
                if tryAgain then
                    tryDP false b.Child
                else
                    failwith "Border found inside border?"
            | :? DockPanel as dp ->
                dp
            | null ->
                invalidArg "sender" "No dockpanel, sender was null"
            | x ->
                x.Dump()
                failwithf "that's no dockpanel, it's a %sstation!" <| x.GetType().Name
        getTemplateChild sender
        |> tryDP true
    
    let fixArrowSize (frame:Frame) =
        let adjustGridControl size (c:Control) =
            c.MinHeight <- size
            c.MinWidth <- size
            c
            |> Option.ofCast<Button>
            |> Option.iter(fun b ->
                let content = b.Content
                let child = getTemplateChild b :?> Grid
                child.MinHeight <- size
                child.MinWidth <- size
            )
        match getDockPanel frame with
        | null -> ()
        | dp ->
            let grid =
                dp
                |> getChildrenOfType<Grid>
                |> Seq.head
            grid
            |> getChildrenOfType<System.Windows.Shapes.Path>
            |> Seq.tryHead
            |> Option.iter (fun path ->
                grid.Children.Remove path
                let size = 40.0
                grid
                |> getChildrenOfType<Control>
                |> Seq.iter (adjustGridControl size)
            )
       
       
        
        ()

let window = Window()
        
let generateDemoFrame gridRow =
    let f = System.Windows.Controls.Frame()
    f.NavigationUIVisibility <- System.Windows.Navigation.NavigationUIVisibility.Visible

    let page =
        Page(Content=Button(Content=sprintf "Hello from row %i (index %i)" gridRow (gridRow + 1)))
    f.Navigate(page) |> ignore
    f.SetValue(Grid.RowProperty,gridRow)
    f
    
let frame2 = generateDemoFrame 2
let grid =
    let g = Grid()
    g.RowDefinitions.Add(RowDefinition(MinHeight=80.,Height=GridLength 80.))
    g.RowDefinitions.Add(RowDefinition(Height=GridLength 200.))
    g.RowDefinitions.Add(RowDefinition(Height=GridLength 200.))

    generateDemoFrame 1
    |> g.Children.Add
    |> ignore<int>
    
    g.Children.Add frame2 |> ignore<int>
    g

window.Content <- grid

window.Dump()
// change size after display
WpfHelpers.fixArrowSize frame2

references.txt

PresentationCore.dll
PresentationFramework.dll
System.Windows.Presentation.dll
WindowsBase.dll