interactions draw fade effect with background colour alpha ~0.5

interactions draw fade effect with background colour alpha ~0.5
looks a bit like bad crt persistence

https://youtu.be/P63VJ2EI79Q (7.8 on MacOS Catalina)

shows up well if scrolling or 'shades of blue' parenthesis colour scheme.
example settings
org.racket-lang.prefs.rktd

(
 (|plt:DrRacket 7.8-splash-max-width| 993)
 (plt:framework-pref:framework:autosaving-on? #t)
 (plt:framework-pref:drracket:materialized-user-docs-versions #hash(("7.8" . #"/Applications/Racket v7.8/doc")))
 (|plt:framework-pref:MacroStepper:SplitContext?| #f)
 (plt:framework-pref:drracket:tools-configuration ())
 (plt:framework-pref:framework:spell-check-strings? #f)
 (plt:framework-pref:framework:backup-files? #t)
 (plt:framework-pref:drracket:logger-receiver-string "error debug@GC debug@PLaneT")
 (plt:framework-pref:htdp:test-engine-window-size #hash((#f . (#f 400 350))))
 (plt:framework-pref:drracket:get-module-path-from-user-size (600 600))
 (plt:framework-pref:framework:spell-check-text? #f)
 (plt:framework-pref:framework:autoload ask)
 (plt:framework-pref:drracket:logger-scroll-to-bottom? #t)
 (|plt:framework-pref:MacroStepper:HighlightFoci?| #t)
 (plt:framework-pref:framework:ask-about-paste-normalization #t)
 (plt:framework-pref:framework:verify-exit #t)
 (plt:framework-pref:drracket:submodules-to-choose-from ((test) (main)))
 (plt:framework-pref:drracket:deinprogramm:sdp:last-set-teachpacks/multi-lib ())
 (plt:framework-pref:framework:do-paste-normalization #t)
 (plt:framework-pref:framework:delete-forward? #t)
 (plt:framework-pref:drracket:defs/ints-labels #t)
 (|plt:framework-pref:MacroStepper:PropertiesPanelPercentage| 1/3)
 (plt:framework-pref:framework:replace-visible? #f)
 (plt:framework-pref:framework:show-periods-in-dirlist #f)
 (plt:framework-pref:drracket:language-dialog:hierlist-default #f)
 (plt:framework-pref:drracket:deinprogramm:last-set-teachpacks/multi-lib ())
 (plt:framework-pref:framework:anchored-search #f)
 (plt:framework-pref:framework:file-dialogs std)
 (plt:framework-pref:external-browser #f)
 (plt:framework-pref:drracket:language-dialog:teaching-hierlist-default #f)
 (|plt:framework-pref:MacroStepper:OneByOne?| #f)
 (plt:framework-pref:framework:search-string ())
 (plt:framework-pref:drracket:open-module-path-last-used "")
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:other #hash())
 (plt:framework-pref:framework:recent-items-window-w 400)
 (plt:framework-pref:drracket:create-executable-gui-type stand-alone)
 (plt:framework-pref:htdp:test-engine-window-position #hash((#f . (0 0 0))))
 (plt:framework-pref:drracket:user-defined-keybindings ())
 (plt:framework-pref:framework:replace-string ())
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:parenthesis #hash())
 (plt:framework-pref:drracket:module-browser:hide-paths (lib))
 (plt:framework-pref:framework:recent-items-window-h 600)
 (plt:framework-pref:drracket:create-executable-gui-base racket)
 (|plt:framework-pref:MacroStepper:ShowHidingPanel?| #t)
 (plt:framework-pref:framework:paren-color-scheme shades-of-blue)
 (plt:framework-pref:test-engine:enable? #t)
 (plt:framework-pref:framework:coloring-active #t)
 (plt:framework-pref:color-scheme-entry:framework:default-text-color #hash())
 (plt:framework-pref:drracket:create-executable-gui-embed-dlls? #t)
 (plt:framework-pref:drracket:multi-file-search:recur? #t)
 (|plt:framework-pref:SyntaxBrowser:Width| 700)
 (plt:framework-pref:color-scheme-entry:framework:misspelled-text-color #hash())
 (plt:framework-pref:drracket:logger-gui-tab-panel-level 0)
 (plt:framework-pref:drracket:multi-file-search:filter? #t)
 (|plt:framework-pref:MacroStepper:Frame:Width| 700)
 (plt:framework-pref:framework:square-bracket:cond/offset (() ()))
 (plt:framework-pref:drracket:multi-file-search:search-check-boxes ((#f) ()))
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:error #hash())
 (plt:framework-pref:drracket:saved-bug-reports ())
 (plt:framework-pref:drracket:multi-file-search:filter-regexp "\\.(rkt|scm|scrbl|ss|rktd|rktl)$")
 (|plt:framework-pref:SyntaxBrowser:DrawArrows?| #t)
 (plt:framework-pref:framework:square-bracket:local (() ()))
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:symbol #hash())
 (plt:framework-pref:drracket:module-language-first-line-special? #t)
 (plt:framework-pref:drracket:multi-file-search:search-string "")
 (|plt:framework-pref:SyntaxBrowser:Height| 600)
 (plt:framework-pref:framework:square-bracket:letrec (() ()))
 (plt:framework-pref:drracket:multi-file-search:directories ())
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:comment #hash())
 (plt:framework-pref:drracket:defns-popup-sort-by-name? #f)
 (plt:framework-pref:drracket:multi-file-search:search-type 1)
 (|plt:framework-pref:SyntaxBrowser:DisplayTaintIcons| char)
 (plt:framework-pref:framework:square-bracket:for/fold (() ()))
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:constant #hash())
 (plt:framework-pref:color-scheme-entry:drracket:check-syntax:imported #hash())
 (plt:framework-pref:drracket:show-line-numbers? #f)
 (plt:framework-pref:drracket:multi-file-search:percentages (1/3 2/3))
 (|plt:framework-pref:MacroStepper:HighlightFrontier?| #t)
 (plt:framework-pref:framework:case-sensitive-search? #f)
 (plt:framework-pref:drracket:unfinished-bug-reports
  (
   (3)
   0
   ()
   0
   ()
   ()
   ()
  ))
 (plt:framework-pref:color-scheme-entry:framework:basic-canvas-background #hash((classic . #4(255 255 205 0.47))))
 (plt:framework-pref:color-scheme-entry:drracket:check-syntax:set!d #hash())
 (plt:framework-pref:drracket:toolbar-state (#f . top))
 (plt:framework-pref:drracket:multi-file-search:frame-size (300 . 400))
 (plt:framework-pref:drracket:online-compilation-default-on #t)
 (|plt:framework-pref:SyntaxBrowser:PropertiesPanelPercentage| 1/3)
 (plt:framework-pref:framework:white-on-black? #f)
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:string #hash())
 (plt:framework-pref:color-scheme-entry:drracket:check-syntax:my-obligation-style-pref #hash())
 (plt:framework-pref:drracket:htdp:last-set-teachpacks/multi-lib ())
 (plt:framework-pref:drracket:multi-file-search:directory (#f))
 (plt:framework-pref:test-engine:test-dock-size (2/3 1/3))
 (|plt:framework-pref:SyntaxBrowser:PropertiesPanelShown| #t)
 (plt:framework-pref:framework:special-meta-key #f)
 (plt:framework-pref:drracket:email "")
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:hash-colon-keyword #hash())
 (plt:framework-pref:color-scheme-entry:drracket:check-syntax:lexically-bound #hash())
 (plt:framework-pref:drracket:defs/ints-horizontal #f)
 (plt:framework-pref:drracket:online-expansion:read-in-defs-errors margin)
 (|plt:framework-pref:MacroStepper:DrawArrows?| #t)
 (plt:framework-pref:framework:any-control+alt-is-altgr #f)
 (plt:framework-pref:drracket:full-name "")
 (plt:framework-pref:framework:delegatee-overview-color (173 216 230 1.0))
 (plt:framework-pref:color-scheme-entry:framework:line-numbers #hash())
 (plt:framework-pref:color-scheme-entry:drracket:check-syntax:unused-require #hash())
 (plt:framework-pref:drracket:recent-language-names (("Determine language from source" #6(#t print mixed-fraction-e #f #t debug) (default) #0() "#lang racket/gui\n" #t #t ((test) (main)) #t)))
 (plt:framework-pref:drracket:online-expansion:variable-errors margin)
 (|plt:framework-pref:MacroStepper:MacroStepLimit| 40000)
 (plt:framework-pref:framework:fraction-snip-style mixed)
 (plt:framework-pref:plt:http-proxy #f)
 (plt:framework-pref:framework:exit-when-no-frames #f)
 (plt:framework-pref:color-scheme-entry:framework:line-numbers-current-line-number-foreground #hash())
 (plt:framework-pref:color-scheme-entry:plt:htdp:test-coverage-off #hash())
 (plt:framework-pref:drracket:show-interactions-on-execute #t)
 (plt:framework-pref:color-scheme-entry:drracket:read-eval-print-loop:error-color #hash())
 (plt:framework-pref:drracket:online-expansion:other-errors margin)
 (plt:framework-pref:drracket:syncheck:show-arrows? #t)
 (plt:framework-pref:framework:standard-style-list:font-name "Menlo")
 (plt:framework-pref:color-scheme-entry:framework:program-contour-current-location-bar #hash())
 (plt:framework-pref:color-scheme-entry:drracket:check-syntax:free-variable #hash())
 (plt:framework-pref:drracket:open-in-tabs #t)
 (plt:framework-pref:color-scheme-entry:plt:module-language:test-coverage-off #hash())
 (plt:framework-pref:drracket:show-killed-dialog #t)
 (|plt:framework-pref:MacroStepper:ExtraNavigation?| #f)
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:keyword #hash())
 (plt:framework-pref:color-scheme-entry:drracket:check-syntax:their-obligation-style-pref #hash())
 (plt:framework-pref:drracket:toolbar-shown #t)
 (plt:framework-pref:color-scheme-entry:drracket:read-eval-print-loop:value-color #hash())
 (plt:framework-pref:drracket:large-letters-font #f)
 (|plt:framework-pref:MacroStepper:IdentifierComparison| "bound-identifier=?")
 (plt:framework-pref:color-scheme-entry:framework:paren-match-color #hash((classic . #4(0 85 0 0.12549019607843137))))
 (plt:framework-pref:color-scheme-entry:drracket:check-syntax:unk-obligation-style-pref #hash())
 (plt:framework-pref:drracket:install-plt-dialog (#t "" ""))
 (plt:framework-pref:color-scheme-entry:drracket:read-eval-print-loop:out-color #hash())
 (plt:framework-pref:drracket:module-language:auto-text "#lang racket/gui\n")
 (|plt:framework-pref:MacroStepper:Frame:Height| 600)
 (plt:framework-pref:framework:last-directory #"/Users/spdegabrielle/Documents/")
 (plt:framework-pref:signatures:enable-checking? #t)
 (plt:framework-pref:color-scheme-entry:framework:failed-search-background-color #hash())
 (plt:framework-pref:color-scheme-entry:drracket:check-syntax:both-obligation-style-pref #hash())
 (plt:framework-pref:drracket:unit-window-size-percentage 88/137)
 (plt:framework-pref:color-scheme-entry:plt:module-language:test-coverage-on #hash())
 (plt:framework-pref:drracket:check-syntax-error-report-window-percentage 1/10)
 (plt:framework-pref:framework:recent-max-count 50)
 (plt:framework-pref:color-scheme-entry:framework:warning-background-color #hash())
 (plt:framework-pref:color-scheme-entry:drracket:syncheck:template-arrow #hash())
 (plt:framework-pref:drracket:module-browser-size-percentage 1/5)
 (plt:framework-pref:color-scheme-entry:drracket:error-background-highlighting #hash())
 (plt:framework-pref:drracket:syncheck:contracts-locked? #f)
 (plt:framework-pref:framework:last-url-string "")
 (plt:framework-pref:color-scheme-entry:framework:line-numbers-when-word-wrapping #hash())
 (plt:framework-pref:color-scheme-entry:drracket:syncheck:unused-identifier #hash())
 (plt:framework-pref:drracket:logging-size-percentage 3/4)
 (plt:framework-pref:color-scheme-entry:drracket:language-name-and-memory-use-at-top-of-interactions #hash())
 (plt:framework-pref:drracket:syncheck:show-blueboxes? #t)
 (plt:framework-pref:framework:recently-opened-sort-by age)
 (plt:framework-pref:color-scheme-entry:framework:syntax-color:scheme:text #hash())
 (plt:framework-pref:color-scheme-entry:drracket:syncheck:document-identifier #hash())
 (plt:framework-pref:drracket:window-position #hash((#f . (0 3 62)) (((0 22 1280 777)) . (0 3 62))))
 (plt:framework-pref:updates:frequency 604800)
 (plt:framework-pref:plt:debug-tool:stack/variable-area 9/10)
 (plt:framework-pref:color-scheme-entry:framework:line-numbers-current-line-number-background #hash())
 (plt:framework-pref:color-scheme-entry:drracket:syncheck:matching-identifiers #hash())
 (plt:framework-pref:drracket:window-size #hash((#f . (#f 687 658)) (((0 22 1280 777)) . (#f 687 658))))
 (plt:framework-pref:color-scheme-entry:stepper:redex-highlight-color #hash())
 (|plt:framework-pref:MacroStepper:ShowRenameSteps?| #f)
 (plt:framework-pref:framework:show-delegate? #f)
 (plt:framework-pref:framework:alt-as-meta #f)
 (plt:framework-pref:drracket:console-previous-exprs ())
 (plt:framework-pref:drracket:backtrace-window-width 400)
 (plt:framework-pref:framework:standard-style-list:weight normal)
 (plt:framework-pref:color-scheme-entry:stepper:reduct-highlight-color #hash())
 (|plt:framework-pref:MacroStepper:DisplayTaintIcons| char)
 (plt:framework-pref:framework:windows-mdi #f)
 (plt:framework-pref:updates:enabled? unset)
 (plt:framework-pref:color-scheme-entry:framework:disabled-background-color #hash())
 (plt:framework-pref:color-scheme-entry:drracket:syncheck:untacked #hash())
 (plt:framework-pref:drracket:backtrace-window-height 300)
 (plt:framework-pref:framework:automatic-parens #f)
 (plt:framework-pref:framework:standard-style-list:smoothing default)
 (plt:framework-pref:color-scheme-entry:stepper:arrow-color #hash())
 (|plt:framework-pref:MacroStepper:RefreshOnResize?| #t)
 (plt:framework-pref:framework:menu-bindings #t)
 (plt:framework-pref:drracket:xml-eliminate-whitespace #t)
 (plt:framework-pref:color-scheme-entry:plt:htdp:test-coverage-on #hash())
 (plt:framework-pref:drracket:backtrace-window-x 0)
 (|plt:framework-pref:MacroStepper:DebugCatchErrors?| #t)
 (plt:framework-pref:framework:verify-change-format #f)
 (plt:framework-pref:updates:last 0)
 (plt:framework-pref:drracket:backtrace-window-y 0)
 (plt:framework-pref:drracket:language-settings ((-32768) (#6(#t print mixed-fraction-e #f #t debug) (default) #0() "#lang racket/gui\n" #t #t ((test) (main)) #t)))
 (plt:framework-pref:framework:auto-set-wrap? #f)
 (plt:framework-pref:color-scheme-entry:stepper:error-color #hash())
 (plt:framework-pref:drracket:gui-installer-pkg-source "/Users/spdegabrielle/Dev/cs")
 (plt:framework-pref:framework:overwrite-mode-keybindings #f)
 (plt:framework-pref:drracket:profile-how-to-count time)
 (plt:framework-pref:framework:display-line-numbers #t)
 (plt:framework-pref:framework:always-use-platform-specific-linefeed-convention #f)
 (plt:framework-pref:drracket:profile:low-color (150 255 150))
 (plt:framework-pref:framework:show-status-line #t)
 (plt:framework-pref:color-scheme-entry:drracket:syncheck:var-arrow #hash())
 (plt:framework-pref:drracket:profile:high-color (255 150 150))
 (plt:framework-pref:framework:col-offsets #f)
 (plt:framework-pref:drracket:child-only-memory-limit 134217728)
 (plt:framework-pref:color-scheme-entry:drracket:syncheck:tail-arrow #hash())
 (plt:framework-pref:framework:line-spacing-add-gap? #t)
 (plt:framework-pref:drracket:profile:scale linear)
 (plt:framework-pref:framework:editor-x-selection-mode #t)
 (plt:framework-pref:framework:standard-style-list:font-size #2(#hash((((1280 777)) . 12)) 12))
 (plt:framework-pref:framework:print-output-mode standard)
 (plt:framework-pref:framework:ascii-art-enlarge #f)
 (plt:framework-pref:framework:highlight-parens #t)
 (plt:framework-pref:drracket:module-overview:label-font-size 12)
 (plt:framework-pref:drracket:most-recent-lang-line "#lang at-exp racket/gui\n")
 (plt:framework-pref:drracket:test-coverage-ask-about-clearing? #t)
 (plt:framework-pref:framework:fixup-parens #t)
 (plt:framework-pref:drracket:module-overview:window-height 500)
 (|plt:framework-pref:MacroStepper:IdentifierPartition| "By macro scopes")
 (plt:framework-pref:drracket:save-files-on-tab-switch? #f)
 (plt:framework-pref:drracket:repl-buffer-size (#t . 1000))
 (plt:framework-pref:framework:color-scheme classic)
 (plt:framework-pref:framework:fixup-open-parens #f)
 (plt:framework-pref:drracket:module-overview:window-width 500)
 (|plt:framework-pref:MacroStepper:PropertiesShown?| #f)
 (plt:framework-pref:drracket:dont-ask-about-saving-files-on-tab-switch? #f)
 (plt:framework-pref:drracket:keybindings-window-size (400 . 600))
 (plt:framework-pref:framework:column-guide-width (#f 102))
 (plt:framework-pref:drracket:different-racket-for-open-collection-path (#f ""))
 (plt:framework-pref:framework:paren-match #t)
 (plt:framework-pref:drracket:module-browser:name-length 1)
 (|plt:framework-pref:MacroStepper:SuppressWarnings?| #f)
 (plt:framework-pref:drracket:inline-overview-shown? #f)
 (plt:framework-pref:drracket:execute-warning-once #f)
 (plt:framework-pref:framework:aspell-dict #f)
 (plt:framework-pref:framework:tabify
  (
   (() ())
   #rx"^begin"
   #rx"^def"
   #rx"^(for\\*?(/|$)|with-)"
   #f
  ))
 (plt:framework-pref:test-engine:test-window:docked? #f)
 (|plt:framework-pref:MacroStepper:MacroHidingMode| "Disable")
 (plt:framework-pref:drracket:coverage-show-overview-bar #t)
 (plt:framework-pref:drracket:switch-to-module-language-automatically? #t)
 (plt:framework-pref:drracket:prefs-debug #f)
 (plt:framework-pref:framework:autosave-delay 30)
 (plt:framework-pref:drracket:define-popup-hidden-prefixes ())
 (|plt:framework-pref:MacroStepper:CloseOnResetConsole?| #t)
 (plt:framework-pref:drracket:default-tools-configuration load)
 (plt:framework-pref:framework:spell-check-on? #f)
 (plt:framework-pref:framework:recently-opened-files/pos ((#"/Users/spdegabrielle/Library/Preferences/org.racket-lang.prefs.rktd" 0 0) (#"/Users/spdegabrielle/Dev/lander/lander2.rkt" 0 0)))
)

Start by reproducing the fade effect in DrRacket on macOS while scrolling or using the “shades-of-blue” parenthesis scheme, using the provided org.racket-lang.prefs.rktd settings. Compare the interaction display with and without the reported background alpha; done means the unwanted persistence is no longer visible.