C# MS V8i SS3, form cut on another laptop

good day

in a Microstation addin (dll) I have a Form which I attach like this

       public static void startMaincoalTool(string unparsed)
        {
            MaincoalTool mcTool = new MaincoalTool();
            mcTool.AttachAsTopLevelForm(Main.addin, true, "MaincoalTool");
            mcTool.Show();
        }

It comes in two modes. In one mode it looks like in the Form Designer, in the second I change the layout a little, hide some controls, make the form shorter. 

                btnUsun.Visible = false;
                gbWyrobisko.Visible = false;
                gbOdcinekWyrobiska.Location = new System.Drawing.Point(5, 95);
                btnZapisz.Location = new System.Drawing.Point(5, 232);
                btnInfo.Location = new System.Drawing.Point(351, 232);
                this.Height = 299;

It works very well on my laptop (1), however on the laptop of my collegue in the smaller version the form is cut at the bootom. Also a specing between the two groupboxes is smaller. 

In the firrst mode, ie. without the layout changed at runtime, form looks exactly the same on both computers.! Changing FormBorderStyle did not help. My laptop's resolution is 1600x900, the collegue's 1920x1080.

What could the reason be and how can I fix it?

regards, Marek