Change button color using keyboard shortcut C# WPF

I'm getting into some C# WPF, and am creating a simple word processor to convert normal text into wiki markup. I am new to WPF and am having trouble with something seemingly minuscule, and hopefully an easy fix.

I have a Bold button on my main form. When pressed it does what I need it to do, which is turn the selected text to bold and vice versa when pressed again. The Bold button also changes a pretty light blue color when pressed, then back to gray when pressed again. So sweet that works...

//Make Bold MAIN method
    static bool isBold = false;
    public static void boldText()
    {
        if (isBold == false)
        {

            TextSelection ts = MainWindow.thisForm.rtbMain.Selection;
           MainWindow.thisForm.btnBold.Background = Brushes.LightBlue;
            if (!ts.IsEmpty)
            {

                ts.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.Bold);
            }
            isBold = !isBold;

        }
        else
        {

            MainWindow.thisForm.btnBold.Background = Brushes.LightGray;
            TextSelection ts = MainWindow.thisForm.rtbMain.Selection;
            ts.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.Normal);
            isBold = !isBold;

        }

    }

My issue now is for some reason when I call the code above using an InputBinding the selected text turns bold but the button color doesn't change... whaaaaA? I have created a custom Command, Execute and CanExecute Commands below:

  public class ToolBar
   {
     //Custom Command
           public static RoutedCommand boldShortCut = new RoutedCommand();

        //For use with Keybindings for BOLD command
            static bool canExecute = true;
            public static void myCommandExecute(object sender, ExecutedRoutedEventArgs e)
            {
                boldText();
                canExecute = !canExecute;
            }
            public static void myCommandCanExecute(object sender, CanExecuteRoutedEventArgs e)
            {
                e.CanExecute = true;
            }

I then create the KeyGesture and InputBindings in the main form's constructor:

public MainWindow()
        {
            InitializeComponent();
            thisForm = this;
            initializeFeatures();

            KeyGesture kg = new KeyGesture(Key.B, ModifierKeys.Control);
            InputBinding ib = new InputBinding(ToolBar.boldShortCut, kg);
            this.InputBindings.Add(ib);
        }

So this all works but for some reason the Bold button isn't changing color when I use the key gesture (CTRL+B). Is there something I need to do in XAML? Any help would be greatly appreciated and please let me know if anything is unclear or additional info is needed. Thanks guys!

The command you are creating (boldShortCut) is never being setup to do anything. A RoutedCommand only fires an event when it is activated. There needs to be a command binding somewhere up the tree that listens for the event and performs some logic.

Take a look at this page for an explanation of how routed commands work:
How to: Create a RoutedCommand

Additionally, the only reason the text turns bold when you press Ctrl+B is because that is a built-in feature of a RichTextBox. In fact, RichTextBox has a whole lot of features that you can hook toolbar buttons up to very easily. You could save yourself a lot of time by learning how to use a RichTextBox before trying to reimplement its existing features.

Here is a good page to get you started: RichTextBox Overview

(For a full list of existing commands that you can hook things up to, see the EditingCommands Class documentation.)