Fix hoverbar fading in when gallery is open

src/PicView.Avalonia/UI/HoverFadeButtonHandler.cs

@@ -2,6 +2,7 @@ using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Threading;
 using PicView.Avalonia.Animations;
+using PicView.Avalonia.Gallery;
 using PicView.Avalonia.Navigation;
 using PicView.Avalonia.ViewModels;
 
@@ -83,7 +84,7 @@ public class HoverFadeButtonHandler
     private bool ShouldShowButton()
     {
         // You may want to extend this with more checks
-        if (!Settings.UIProperties.ShowAltInterfaceButtons)
+        if (!Settings.UIProperties.ShowAltInterfaceButtons || GalleryFunctions.IsFullGalleryOpen)
         {
             return false;
         }