I have an app that uses a transparent background of a Windows Form with an embedded PictureBox. I draw in the picture box and with versions of Windows 10 before the Creators update I could click on the visible parts of the picture box image as well as the buttons on a toolbar at the bottom of my form. I use the transparencyKey color setting to match the form background color. Here is a snippet of C# code for the Form.
ecgPictureBox.BackColor = Color.Transparent;
this.BackColor = Color.Gray;
this.TransparencyKey = Color.Gray;
After the Creators update, when I click on visible parts of the form (including buttons on a toolbar at the bottom) most of the time the click "falls through" to the underlying window, though there a few odd points where the click does appear to be absorbed by the form. This all worked perfectly on previous versions. Here are two pictures Not working (Creators update) Working! (earlier version Windows 10
Anyone else have a problem with WinForms transparency after the Creators update, and any idea what is going on or how to fix it?