c# - Custom TabControl display issues -

i've been writing custom drawn tab control few days , part pretty , amazing job ... except when use on windows 10 computer (at run-time).

i've gone basic few lines of code trace error , can't life of me figure out.

below code being used, in nutshell i'm designing horizontal aligned tab control.

using system.drawing; using system.windows.forms;  namespace windowsformsapplication1.ui {     class tabcontroltest : tabcontrol     {         public tabcontroltest()         {             alignment = tabalignment.left;             sizemode = tabsizemode.fixed;         }     } } 

i've added custom tab control form, added couple of group boxes reference purposes , changed background colour of form grey can see tab control.

now, at design time 2 group boxes (1 in tab control, 1 on form) align perfectly.

but @ run-time see different result.

as can see tab part of control larger @ design time , resulting change means contexts of tab have moved.

if on windows 7 computer displayed appears @ design time, should!

i've added imagesize makes no difference.

itemsize = new system.drawing.size(30, 150); 

i've reinstalled vs on (win10) development machine. i'm @ loss explain why , how resolve this.

any/all immensely appreciated.

looking @ tab width in comparison images, believe issue caused automatic windows control scaling. found dpiaware option automatically set when it's run within visual studio , reverts default windows scaling windows implements when outside visual studio.

to prevent auto-scaling when run outside visual studio altogether need notify os you're application dpiaware calling win32 p/invoke setprocessdpiaware() method within main() before application.run() called, example below demonstrates. let controls use native resolution designing coordinates from.

static class program {     [system.runtime.interopservices.dllimport("user32.dll")]     private static extern bool setprocessdpiaware();      static void main(string[] args)     {         if (environment.osversion.version.major >= 6)             setprocessdpiaware();          application.run(new uimonitor());     } } 

alternatively, if want keep scaling, may able set groupbox location based off width of tab control instead of specific location. (or using combination of control measurements instead of exact picel placement.)