How do I only disable a section in a certain InstType, but force it on otherwise (even in the "Custom" InstType)?

I have a Section that is set to RO and occurs in all InstTypes except for a special one.

When the user first selects the special InstType and then selects "Custom" as the InstType the section is unchecked and can't be checked again in the "Custom" InstType.

So everything is fine except that when the users selects the "Custom" InstType the Section should always be checked again.

Only in the special InstType use case it should be unchecked.

How can I achieve this?

Solution

You can enforce whatever logic you want in .onSelChange:

!include WinMessages.nsh
!include LogicLib.nsh
!include Sections.nsh

Page Components
Page InstFiles

InstType "Normal1"
!define CIT_Special 1
InstType "Special"
InstType "Normal2"

Section Foo
SectionIn 1 2 3
SectionEnd

Section Bar SEC_Special
SectionIn 1 3
SectionIn RO
SectionEnd

Section Baz
SectionIn 1 2 ;3 << Not the same as Foo just to have some sort of difference
SectionEnd

Function .onSelChange
;Normally you would call GetCurInstType here, but it seems we need a little hack to detect the custom section
FindWindow $1 "#32770" "" $HWNDPARENT
GetDlgItem $1 $1 0x3F9
SendMessage $1 ${CB_GETCURSEL} 0 0 $2
SendMessage $1 ${CB_GETITEMDATA} $2 0 $2
${If} $2 = ${CIT_Special}
    !insertmacro UnselectSection ${SEC_Special}
${Else}
    !insertmacro SelectSection ${SEC_Special}
${EndIf}
FunctionEnd