Repository: flutter
Issue: Flutter demo home page banner widget buggy when hovering over increment button on linux desktop
Labels: engine,platform-linux,c: rendering,a: desktop,P2,team-linux,triaged-linux

## Steps to Reproduce

<!-- You must include full steps to reproduce so that we can reproduce the problem. -->

1. Run `flutter create app`.
2. Run `flutter run -d linux`

**Expected results:** <!-- what did you want to see? -->

No rendering bugs with banner widget.
**Actual results:** <!-- what did you see? -->

![image](https://user-images.githubusercontent.com/28828395/101217052-a8117f00-364e-11eb-9bfd-03f04422725d.png)

<!--
      Run your application with `flutter run --verbose` and attach all the
      log output below between the lines with the backticks. If there is an
      exception, please see if the error message includes enough information
      to explain how to solve the issue.
-->

```
[  +54 ms] executing: [/home/sabetai/snap/flutter/common/flutter/] git -c
log.showSignature=false log -n 1 --pretty=format:%H
[  +32 ms] Exit code 0 from: git -c log.showSignature=false log -n 1
--pretty=format:%H
[        ] a7f5fd5360007518644597c60a1f2169eacccc2b
[        ] executing: [/home/sabetai/snap/flutter/common/flutter/] git tag
--points-at a7f5fd5360007518644597c60a1f2169eacccc2b
[  +51 ms] Exit code 0 from: git tag --points-at
a7f5fd5360007518644597c60a1f2169eacccc2b
[   +1 ms] 1.25.0-4.0.pre
[  +61 ms] executing: [/home/sabetai/snap/flutter/common/flutter/] git rev-parse
--abbrev-ref --symbolic @{u}
[   +5 ms] Exit code 0 from: git rev-parse --abbrev-ref --symbolic @{u}
[        ] origin/dev
[        ] executing: [/home/sabetai/snap/flutter/common/flutter/] git ls-remote
--get-url origin
[   +3 ms] Exit code 0 from: git ls-remote --get-url origin
[        ] https://github.com/flutter/flutter.git
[  +36 ms] executing: [/home/sabetai/snap/flutter/common/flutter/] git rev-parse
--abbrev-ref HEAD
[   +5 ms] Exit code 0 from: git rev-parse --abbrev-ref HEAD
[        ] dev
[  +39 ms] Artifact Instance of 'AndroidGenSnapshotArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'AndroidInternalBuildArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'IOSEngineArtifacts' is not required, skipping
update.
[        ] Artifact Instance of 'FlutterWebSdk' is not required, skipping
update.
[   +1 ms] Artifact Instance of 'WindowsEngineArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'MacOSEngineArtifacts' is not required, skipping
update.
[        ] Artifact Instance of 'LinuxEngineArtifacts' is not required, skipping
update.
[        ] Artifact Instance of 'LinuxFuchsiaSDKArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'MacOSFuchsiaSDKArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'FlutterRunnerSDKArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'FlutterRunnerDebugSymbols' is not required,
skipping update.
[  +50 ms] executing: /home/sabetai/Android/Sdk/platform-tools/adb devices -l
[  +10 ms] Artifact Instance of 'AndroidGenSnapshotArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'AndroidInternalBuildArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'IOSEngineArtifacts' is not required, skipping
update.
[        ] Artifact Instance of 'FlutterWebSdk' is not required, skipping
update.
[        ] Artifact Instance of 'WindowsEngineArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'MacOSEngineArtifacts' is not required, skipping
update.
[   +1 ms] Artifact Instance of 'LinuxFuchsiaSDKArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'MacOSFuchsiaSDKArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'FlutterRunnerSDKArtifacts' is not required,
skipping update.
[        ] Artifact Instance of 'FlutterRunnerDebugSymbols' is not required,
skipping update.
[  +46 ms] executing: /home/sabetai/Android/Sdk/platform-tools/adb devices -l
[  +13 ms] Skipping pub get: version match.
[  +95 ms] Generating
/home/sabetai/Flutter/codebook/android/app/src/main/java/io/flutter/plugins/Gene
ratedPluginRegistrant.java
[  +61 ms] Initializing file store
[   +5 ms] Skipping target: gen_localizations
[   +4 ms] complete
[   +4 ms] Launching lib/main.dart on Linux in debug mode...
[   +4 ms] /home/sabetai/snap/flutter/common/flutter/bin/cache/dart-sdk/bin/dart
--disable-dart-dev
/home/sabetai/snap/flutter/common/flutter/bin/cache/artifacts/engine/linux-x64/f
rontend_server.dart.snapshot --sdk-root
/home/sabetai/snap/flutter/common/flutter/bin/cache/artifacts/engine/common/flut
ter_patched_sdk/ --incremental --target=flutter --debugger-module-names
--experimental-emit-debug-metadata -Ddart.developer.causal_async_stacks=true
--output-dill /tmp/flutter_tools.SVNSTL/flutter_tool.ALRIST/app.dill --packages
/home/sabetai/Flutter/codebook/.dart_tool/package_config.json
-Ddart.vm.profile=false -Ddart.vm.product=false --enable-asserts
--track-widget-creation --filesystem-scheme org-dartlang-root
--initialize-from-dill build/cache.dill.track.dill
[  +15 ms] Building Linux application...
[  +23 ms] <- compile package:codebook/main.dart
[   +2 ms] executing: [build/linux/debug/] cmake -G Ninja
-DCMAKE_BUILD_TYPE=Debug /home/sabetai/Flutter/codebook/linux
[  +10 ms] List of devices attached
[   +1 ms] List of devices attached
[  +29 ms] -- Configuring done
[   +4 ms] -- Generating done
[        ] -- Build files have been written to:
/home/sabetai/Flutter/codebook/build/linux/debug
[   +3 ms] executing: ninja -C build/linux/debug install
[   +4 ms] ninja: Entering directory `build/linux/debug'
[+3152 ms] [1/5] Generating
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/libflutter_linux_gtk.so,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_basic_me
ssage_channel.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_binary_c
odec.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_binary_m
essenger.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_dart_pro
ject.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_engine.h
,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_json_mes
sage_codec.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_json_met
hod_codec.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_message_
codec.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_method_c
all.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_method_c
hannel.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_method_c
odec.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_method_r
esponse.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_plugin_r
egistrar.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_plugin_r
egistry.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_standard
_message_codec.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_standard
_method_codec.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_string_c
odec.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_value.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/fl_view.h,
/home/sabetai/Flutter/codebook/linux/flutter/ephemeral/flutter_linux/flutter_lin
ux.h, _phony_
[   +3 ms] [  +53 ms] executing: [/home/sabetai/snap/flutter/common/flutter/]
git -c log.showSignature=false log -n 1 --pretty=format:%H
[        ] [  +26 ms] Exit code 0 from: git -c log.showSignature=false log -n 1
--pretty=format:%H
[        ] [        ] a7f5fd5360007518644597c60a1f2169eacccc2b
[        ] [        ] executing: [/home/sabetai/snap/flutter/common/flutter/]
git tag --points-at a7f5fd5360007518644597c60a1f2169eacccc2b
[        ] [   +9 ms] Exit code 0 from: git tag --points-at
a7f5fd5360007518644597c60a1f2169eacccc2b
[        ] [        ] 1.25.0-4.0.pre
[        ] [  +32 ms] executing: [/home/sabetai/snap/flutter/common/flutter/]
git rev-parse --abbrev-ref --symbolic @{u}
[        ] [   +4 ms] Exit code 0 from: git rev-parse --abbrev-ref --symbolic
@{u}
[        ] [        ] origin/dev
[        ] [        ] executing: [/home/sabetai/snap/flutter/common/flutter/]
git ls-remote --get-url origin
[        ] [   +3 ms] Exit code 0 from: git ls-remote --get-url origin
[        ] [        ] https://github.com/flutter/flutter.git
[        ] [  +30 ms] executing: [/home/sabetai/snap/flutter/common/flutter/]
git rev-parse --abbrev-ref HEAD
[        ] [   +7 ms] Exit code 0 from: git rev-parse --abbrev-ref HEAD
[        ] [        ] dev
[        ] [  +39 ms] Artifact Instance of 'AndroidGenSnapshotArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'AndroidInternalBuildArtifacts' is
not required, skipping update.
[        ] [        ] Artifact Instance of 'IOSEngineArtifacts' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'FlutterWebSdk' is not required,
skipping update.
[        ] [   +2 ms] Artifact Instance of 'WindowsEngineArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'MacOSEngineArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'LinuxEngineArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'LinuxFuchsiaSDKArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'MacOSFuchsiaSDKArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'FlutterRunnerSDKArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'FlutterRunnerDebugSymbols' is not
required, skipping update.
[        ] [  +43 ms] Artifact Instance of 'MaterialFonts' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'GradleWrapper' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'AndroidGenSnapshotArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'AndroidInternalBuildArtifacts' is
not required, skipping update.
[        ] [        ] Artifact Instance of 'IOSEngineArtifacts' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'FlutterWebSdk' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'FlutterSdk' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'WindowsEngineArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'MacOSEngineArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'LinuxEngineArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'LinuxFuchsiaSDKArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'MacOSFuchsiaSDKArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'FlutterRunnerSDKArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'FlutterRunnerDebugSymbols' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'IosUsbArtifacts' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'IosUsbArtifacts' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'IosUsbArtifacts' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'IosUsbArtifacts' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'IosUsbArtifacts' is not required,
skipping update.
[        ] [        ] Artifact Instance of 'FontSubsetArtifacts' is not
required, skipping update.
[        ] [        ] Artifact Instance of 'PubDependencies' is not required,
skipping update.
[        ] [  +76 ms] Initializing file store
[        ] [   +4 ms] Done initializing file store
[        ] [  +24 ms] Skipping target: gen_localizations
[        ] [+1544 ms] Skipping target: unpack_linux
[        ] [ +329 ms] Skipping target: kernel_snapshot
[        ] [ +249 ms] Skipping target: debug_bundle_linux_assets
[        ] [        ] Persisting file store
[        ] [   +7 ms] Done persisting file store
[        ] [   +4 ms] build succeeded.
[        ] [   +6 ms] "flutter assemble" took 2,307ms.
[        ] [ +193 ms] ensureAnalyticsSent: 190ms
[        ] [   +2 ms] Running shutdown hooks
[        ] [        ] Shutdown hooks complete
[        ] [        ] exiting with code 0
[ +326 ms] [2/5] Building CXX object
CMakeFiles/codebook.dir/flutter/generated_plugin_registrant.cc.o
[  +24 ms] [3/5] Building CXX object CMakeFiles/codebook.dir/my_application.cc.o
[  +80 ms] [4/5] Linking CXX executable intermediates_do_not_run/codebook
[        ] [4/5] Install the project...
[   +8 ms] -- Install configuration: "Debug"
[  +15 ms] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/codebook
[        ] -- Set runtime path of
"/home/sabetai/Flutter/codebook/build/linux/debug/bundle/codebook" to
"$ORIGIN/lib"
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/icudtl.dat
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/lib/libflutter_linux_gtk
.so
[  +80 ms] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/Font
Manifest.json
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/font
s
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/font
s/MaterialIcons-Regular.otf
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/Asse
tManifest.json
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/pack
ages
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/pack
ages/cupertino_icons
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/pack
ages/cupertino_icons/assets
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/pack
ages/cupertino_icons/assets/CupertinoIcons.ttf
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/kern
el_blob.bin
[  +23 ms] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/vers
ion.json
[        ] -- Installing:
/home/sabetai/Flutter/codebook/build/linux/debug/bundle/data/flutter_assets/NOTI
CES
[  +10 ms] Building Linux application... (completed in 3.8s)
[ +169 ms] Observatory URL on device: http://127.0.0.1:37743/77fqOoBQzac=/
[   +3 ms] Caching compiled dill
[  +32 ms] Connecting to service protocol: http://127.0.0.1:37743/77fqOoBQzac=/
[   +4 ms] Launching a Dart Developer Service (DDS) instance at
http://127.0.0.1:0, connecting to VM service at
http://127.0.0.1:37743/77fqOoBQzac=/.
[ +174 ms] DDS is listening at http://127.0.0.1:38101/VAq69KSUL0A=/.
[  +66 ms] Successfully connected to service protocol:
http://127.0.0.1:37743/77fqOoBQzac=/
[  +14 ms] DevFS: Creating new filesystem on the device (null)
[  +11 ms] DevFS: Created new filesystem on the device
(file:///tmp/codebookGGHXSO/codebook/)
[   +1 ms] Updating assets
[  +67 ms] Syncing files to device Linux...
[   +1 ms] <- reset
[        ] Compiling dart to kernel with 0 updated files
[   +1 ms] <- recompile package:codebook/main.dart
4e8ed7d6-3a13-4041-8e08-9ecc6584712a
[        ] <- 4e8ed7d6-3a13-4041-8e08-9ecc6584712a
[  +59 ms] Updating files.
[        ] DevFS: Sync finished
[   +1 ms] Syncing files to device Linux... (completed in 64ms)
[        ] Synced 0.0MB.
[        ] <- accept
[   +6 ms] Connected to _flutterView/0x19a66c0.
[   +2 ms] Flutter run key commands.
[   +2 ms] r Hot reload. 🔥🔥🔥
[   +1 ms] R Hot restart.
[        ] h Repeat this help message.
[        ] d Detach (terminate "flutter run" but leave application running).
[        ] c Clear the screen
[        ] q Quit (terminate the application on the device).
[        ] An Observatory debugger and profiler on Linux is available at:
           http://127.0.0.1:38101/VAq69KSUL0A=/
[        ] Running with unsound null safety
[        ] For more information see
https://dart.dev/null-safety/unsound-null-safety
[+55319 ms] Application finished.
```

<!--
     Run `flutter analyze` and attach any output of that command below.
     If there are any analysis errors, try resolving them before filing this issue.
-->

```
No issues found! (ran in 9.5s)
```

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[✓] Flutter (Channel dev, 1.25.0-4.0.pre, on Linux, locale en_CA.UTF-8)
    • Flutter version 1.25.0-4.0.pre at /home/sabetai/snap/flutter/common/flutter
    • Framework revision a7f5fd5360 (4 days ago), 2020-11-30 13:14:13 +0100
    • Engine revision 20caf54969
    • Dart version 2.12.0 (build 2.12.0-76.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
    • Android SDK at /home/sabetai/Android/Sdk
    • Platform android-30, build-tools 30.0.2
    • Java binary at: /usr/bin/java
    • Java version Java(TM) SE Runtime Environment (build 15.0.1+9-18)
    • All Android licenses accepted.

[✓] Linux toolchain - develop for Linux desktop
    • clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
    • cmake version 3.10.2
    • ninja version 1.8.2
    • pkg-config version 0.29.1

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/linux#android-setup for detailed instructions).

[✓] Connected device (1 available)
    • Linux (desktop) • linux • linux-x64 • Linux

! Doctor found issues in 1 category.
```

</details>