Linux: fix tray icon menu build with INDICATOR=1

[ElCruncharino]

Problem

Building with INDICATOR=1 fails on wxWidgets 3.2:

Forms/MainFrame.cpp:1630:134: error: cannot convert 'wxString' to 'const gchar*'

Four of the five tray menu labels in ShowTaskBarIcon() pass a wxString straight to gtk_menu_item_new_with_label(), which wants a const gchar*. The fifth (SHOW_TC/HIDE_TC) already calls .mb_str() and compiles fine. INDICATOR is opt-in and off by default, so perhaps this has gone unnoticed?

Change

Add the missing .mb_str() to the other four labels. No behavior change, just makes it compile.

Testing

Built with make INDICATOR=1 WITHFUSE3=1 against wxWidgets 3.2.8 and libayatana-appindicator3. Confirmed the resulting binary links against libayatana-appindicator3 and shows a working tray icon.

[idrassi]

Thanks for the PR.

I had not hit this locally with make INDICATOR=1 on several distributions, including with wxWidgets 3.2.8. That is expected on builds where wx still allows the unsafe implicit wxString => const char* conversion (wxUSE_UNSAFE_WXSTRING_CONV without wxNO_UNSAFE_WXSTRING_CONV). On configurations that disable that conversion, the four bare LangString[...] arguments fail exactly as you reported, while the existing .mb_str() on the show/hide item still compiles.

So this is a real portability fix (the inconsistency dates back to the original INDICATOR support in #815), not a general "wx 3.2 is broken" issue.

Could you confirm the distribution and whether your environment defines wxNO_UNSAFE_WXSTRING_CONV (or similar)? For the record, sibling PR #1822 mentions openSUSE Tumbleweed, is that the same setup?

Aside from that, the change looks good and matches the existing style. I will merge it.

[ElCruncharino]

Confirmed on the exact box: openSUSE Tumbleweed, wxWidgets 3.2.8 (gtk3-unicode-3.2, official distro package).

I don't think its wxNO_UNSAFE_WXSTRING_CONV. That macro isn't defined anywhere in this package's setup.h, and I get the identical compile error whether I force it or not. wxUSE_STL, which this package builds with (wxUSE_STL=1 → wxUSE_STD_STRING_CONV_IN_WXSTRING=1). In wx/string.h, the whole operator const char*()/operator const void*() block is wrapped in #if !wxUSE_STD_STRING_CONV_IN_WXSTRING, so in STL-mode builds that operator doesn't exist at all. wxNO_UNSAFE_WXSTRING_CONV doesn't appear to even come into play.

I rebuilt master with make INDICATOR=1 WITHFUSE3=1 on this box and reproduced the exact 4 errors at the exact reported lines; applying this PR's diff fixed it and produced a working binary linked against libayatana-appindicator3.