[win32] Widget constructor calls overrideable public method; breaks EGit's `FindToolbar`

[fedejeanne]

Mirror ticket for:

• [win32] Widget constructor calls overrideable public method; breaks EGit's FindToolbar eclipse-platform/eclipse.platform.swt#2733

[fedejeanne]

The issue was solved by:

• Do not call addListener in Widget::registerDPIChangeListener #2733 eclipse-platform/eclipse.platform.swt#2736

I found other usages and fixed them in:

• Do not call addListener in constructor of Item #2733 eclipse-platform/eclipse.platform.swt#2738
• Do not call addListener in constructors of CCombo and StyledText #2733 eclipse-platform/eclipse.platform.swt#2739

[fedejeanne]

I moved it to In Review since there is still one PR open but I considered the regression to be fixed so this has lower priority.

[fedejeanne]

Since I found out that the remaining calls have been introduced recently by @amartya4256 :

• Design improvement for scaling win32 widgets eclipse-platform/eclipse.platform.swt#2483

I decided to keep the regression tag. The code is new, it could break consumers once it hits the next release. It should be fixed promptly.

Important

Disclaimer: it would be difficult to break a consumer, since it would have to:

• Extend one of the classes (CCombo / StyledText)
• Override the public method addListener(int, Listener)
• Use some uninitialized field in it

Nevertheless, the PR is about containing risk.