Вы можете добавить дополнительные границы, создав дополнительные окна:
OutFile Test.exe
RequestExecutionLevel user
Page License "" onLicShow
Page InstFiles
!include nsDialogs.nsh ; WS_*
Function onLicShow
GetDlgItem $5 $hWndParent 0xFFFFFFFF
ShowWindow $5 0 ; Hide the original line
System::Call 'USER32::GetWindowRect(pr5,@r0)' ; NSIS v3+
System::Call 'USER32::MapWindowPoints(p0, p$hWndParent, pr0, i1)'
System::Call '*$0(i.r1,i.r2,i.r3,i.r4)'
IntOp $2 $2 - 2 ; Adjust a little up
System::Call 'USER32::CreateWindowEx(i0, t"STATIC", p0, i ${WS_VISIBLE}|${WS_CHILD}, i 0, i r2, i 9999, i 4, p$hWndParent, p0, p0, p0)p.r0'
SetCtlColors $0 "" 0xff0000 ; Red
System::Call 'USER32::CreateWindowEx(i0, t"STATIC", p0, i ${WS_VISIBLE}|${WS_CHILD}, i 0, i 0, i 4, i 9999, p$hWndParent, p0, p0, p0)p.r0'
SetCtlColors $0 "" 0x00ff00 ; Green
System::Call 'USER32::GetClientRect(p$hWndParent,@r0)' ; NSIS v3+
System::Call '*$0(i,i,i.r3,i)'
IntOp $3 $3 - 4 ; X = Window width - border width
System::Call 'USER32::CreateWindowEx(i0, t"STATIC", p0, i ${WS_VISIBLE}|${WS_CHILD}, i $3, i 0, i 4, i 9999, p$hWndParent, p0, p0, p0)p.r0'
SetCtlColors $0 "" 0xffff00 ; Yellow
System::Call 'USER32::CreateWindowEx(i0, t"STATIC", p0, i ${WS_VISIBLE}|${WS_CHILD}, i 0, i 0, i 9999, i 4, p$hWndParent, p0, p0, p0)p.r0'
SetCtlColors $0 "" 0xffffff ; White
FindWindow $1 "#32770" "" $hWndParent ; Find the inner dialog
System::Call 'USER32::CreateWindowEx(i0, t"STATIC", p0, i ${WS_VISIBLE}|${WS_CHILD}, i 0, i 0, i 9999, i 7, p$1, p0, p0, p0)p.r0'
SetCtlColors $0 "" 0x0000ff ; Blue
FunctionEnd
Окна во внутреннем диалоге видны только на этой странице, другие окна видны на всех страницах.