After android text keyboard hided custom keyboard displayed twice - xamarin.android

Question

In my activity class i use both custom keyboard and android soft text keyboard. Android text soft keyboard resizes activity layout. If I open custom keyboard while soft keyboard is opened, the last one hides and layout expands back. But I open custom keyboard right after call
InputMethodManager imm = (InputMethodManager)context.GetSystemService(Context.InputMethodService);
imm.HideSoftInputFromWindow(view.WindowToken, 0);
Here view is view with custom keyboard.
And I face the problem when custom keyboard draws twice:
When android soft keyboard is hidden, but layout is not expanded back yet. In that case custom keyboard appears at the top half of the screen.
After layout is expanded back. In that case custom keyboard appears on the bottom half of the screen.
What i want to do is somehow avoid two keyboards simultaneous appearance.
In activity code i use only SoftInput.StateAlwaysHidden WindowSoftInputMode. SoftInput.AdjustPan is not convenient because in that case some views can be hidden by android keyboard.

Answer 1

After hours of internet search the answer has been found. Pspdfkit has great post.
And with small investigation it has been rewritten on C# in Oncreate method:
private View decorView;
private int lastVisibleDecorViewHeight = 0;
decorView = Window.DecorView;
decorView.ViewTreeObserver.GlobalLayout += (sender, args) =>
{
Rect windowVisibleDisplayFrame = new Rect();
decorView.GetWindowVisibleDisplayFrame(windowVisibleDisplayFrame);
int visibleDecorViewHeight = windowVisibleDisplayFrame.Height();
if (lastVisibleDecorViewHeight != 0)
{
if (lastVisibleDecorViewHeight > visibleDecorViewHeight)
{
OnSoftKeyboardShown();
}
else if (lastVisibleDecorViewHeight < visibleDecorViewHeight)
{
OnSoftKeyboardHidden();
if (!isAndroidSoftKeyboardShown && customKeyboardRequested)
{
Keyboard.RequestCustomKeyboard(requestedCustomKeyboardType);
customKeyboardRequested = false;
}
}
}
lastVisibleDecorViewHeight = visibleDecorViewHeight;
};
Hope this will help someone with similar problems.