WPF window does not exceed the screen

Question

I have the following code:

    System.Windows.Point ponto = PointToScreen(Mouse.GetPosition(this));

    JanelaAbrir.Left = ponto.X;
    JanelaAbrir.Top = ponto.Y;

    JanelaAbrir.ShowDialog();

It opens the Window in mouse position, but this window can exceed the limits of the monitor, how can I make it not to exceed the limits?

To illustrate better follows a picture:

When opening the window exceeds the edge, screen limit (monitor), preventing the user to see the full window, forcing to drag.

Answer 1

One hypothesis is, in this case, the mouse coordinates do not set the upper left corner of the window but the upper right corner.
The same can be done if the window does not fit vertically, instead of setting the upper left corner define the lower left corner.
If both situations occur, the lower right corner shall be considered.

int x = coordenada x do rato;
int y = coordenada y do rato;
int maxX = largura da tela;
int maxY = altura da tela;
int largura = largura da janela;
int altura = altura da janela;

if(x + largura > maxX) JanelaAbrir.Left = x - Largura;
else JanelaAbrir.Left = x;
if(y + altura > maxY) JanelaAbrir.Top = y - altura;
else JanelaAbrir.Top = y;

This is valid if the window dimensions are less than half the screen dimensions and the origin of the coordinates is in the upper left corner of the screen.