Don't update m_positionLine in paintEvent

[Veratil]

Fixes #5863 (for real this time)

This extra update in paintEvent was causing the misalignment in the piano keys (and actually anywhere the position line was in the window). There is still a very small glitch of the line height when resizing, but this is a small issue I can fix in another PR later.

[LmmsBot]

🤖 Hey, I'm @LmmsBot from github.com/lmms/bot and I made downloads for this pull request, click me to make them magically appear! 🎩

Windows

• Windows 32-bit: lmms-1.3.0-alpha.1.85%2Bgf0e04cd97-mingw-win32.exe (build link)
• Windows 64-bit: lmms-1.3.0-alpha.1.85%2Bgf0e04cd97-mingw-win64.exe (build link)
• Windows 32-bit: lmms-1.3.0-alpha-msvc2017-win32.exe (build link)
• Windows 64-bit: lmms-1.3.0-alpha-msvc2017-win64.exe (build link)

Linux

• Linux (AppImage): lmms-1.3.0-alpha.1.85%2Bgf0e04cd-linux-x86_64.AppImage (build link)

macOS

• macOS : lmms-1.3.0-alpha.1.85%2Bgf0e04cd97-mac10.14.dmg (build link)

🤖

{"platform_name_to_artifacts": {"Windows": [{"artifact": {"title": {"title": "32-bit", "platform_name": "Windows"}, "link": {"link": "https://13235-15778896-gh.circle-artifacts.com/0/lmms-1.3.0-alpha.1.85%2Bgf0e04cd97-mingw-win32.exe"}}, "build_link": "https://circleci.com/gh/LMMS/lmms/13235?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link"}, {"artifact": {"title": {"title": "64-bit", "platform_name": "Windows"}, "link": {"link": "https://13234-15778896-gh.circle-artifacts.com/0/lmms-1.3.0-alpha.1.85%2Bgf0e04cd97-mingw-win64.exe"}}, "build_link": "https://circleci.com/gh/LMMS/lmms/13234?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link"}, {"artifact": {"title": {"title": "32-bit", "platform_name": "Windows"}, "link": {"link": "https://ci.appveyor.com/api/buildjobs/1a75o55en9ropsj9/artifacts/build/lmms-1.3.0-alpha-msvc2017-win32.exe"}}, "build_link": "https://ci.appveyor.com/project/Lukas-W/lmms/builds/38426809"}, {"artifact": {"title": {"title": "64-bit", "platform_name": "Windows"}, "link": {"link": "https://ci.appveyor.com/api/buildjobs/reun7q77fojjs99s/artifacts/build/lmms-1.3.0-alpha-msvc2017-win64.exe"}}, "build_link": "https://ci.appveyor.com/project/Lukas-W/lmms/builds/38426809"}], "Linux": [{"artifact": {"title": {"title": "(AppImage)", "platform_name": "Linux"}, "link": {"link": "https://13233-15778896-gh.circle-artifacts.com/0/lmms-1.3.0-alpha.1.85%2Bgf0e04cd-linux-x86_64.AppImage"}}, "build_link": "https://circleci.com/gh/LMMS/lmms/13233?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link"}], "macOS": [{"artifact": {"title": {"title": "", "platform_name": "macOS"}, "link": {"link": "https://13231-15778896-gh.circle-artifacts.com/0/lmms-1.3.0-alpha.1.85%2Bgf0e04cd97-mac10.14.dmg"}}, "build_link": "https://circleci.com/gh/LMMS/lmms/13231?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link"}]}, "commit_sha": "2d1200acb69734c45bc4089c3a38dd3349d4a6b0"}

[superpaik]

While the resizing seem to work almost ok regarding the keys of the pianoroll, there are some issues with the notes (see attached animated gif) that are misaligned with the pianoroll keys. The misaligned is corrected when the cursors enters the pianoroll screen.
Also, maybe it's not related to this PR, when in 150% vertical zooming, some notes names (G, D and C) seem to not have enough space to be written and are "cut" by the left. Only in 150%, not with any other vertical zoom. Tested on windows 10.

[Veratil]

While the resizing seem to work almost ok regarding the keys of the pianoroll, there are some issues with the notes (see attached animated gif) that are misaligned with the pianoroll keys. The misaligned is corrected when the cursors enters the pianoroll screen.

I'll look into that one next. Thanks!

Also, maybe it's not related to this PR, when in 150% vertical zooming, some notes names (G, D and C) seem to not have enough space to be written and are "cut" by the left. Only in 150%, not with any other vertical zoom.

Not related, but I believe another PR is touching this code and gives it more draw space.

---

So other than those two separate issues, this PR looks good then I believe. 👍

[Veratil]

Merging tomorrow unless anyone objects.