Find and replace, changing case
This is done with the modifiers \u\U\l\L, where \u and \l will upper/lowercase a single character, and \U and \L will upper/lowercase the rest of the matching group.
The modifiers can be stacked and appear before the referenced group in replace.
ie: \u\u\u$1 or \l\U$1
High contrast
These are the section and tab borders from the default high contrast theme.
src/vs/workbench/common/theme.ts,
src/vs/platform/theme/common/colorRegistry.ts
This can be placed into settings to overlay high contrast onto another theme.
"workbench.colorCustomizations": {
"contrastBorder": "#6FC3DF",
"contrastActiveBorder": "#F38518",
"focusBorder": "#F38518",
"peekView.border": "#6FC3DF",
"tab.border": "#6FC3DF",
"tab.lastPinnedBorder": "#6FC3DF",
"tab.activeBorder": "#00000000" ,
"tab.unfocusedActiveBorder": "#00000000" ,
"tab.activeBorderTop": "#00000000" ,
"tab.unfocusedActiveBorderTop": "#00000000" ,
"tab.activeModifiedBorder": "#00000000" ,
"statusBar.focusBorder": "#00000000" ,
"activityBar.inactiveForeground": "#666666", // 0xff * 0.4
"activityBar.activeBorder": "#6FC3DF" ,
"activityBar.foreground": "#6FC3DF" ,
"editorGroupHeader.border": "#6FC3DF" ,
"editorGroupHeader.tabsBorder": "#6FC3DF" ,
"editorGroup.border": "#6FC3DF" ,
"editorGroup.dropIntoPromptBorder": "#6FC3DF" ,
"sideBySideEditor.verticalBorder": "#6FC3DF" ,
"sideBySideEditor.horizontalBorder": "#6FC3DF" ,
"panel.border": "#6FC3DF" ,
"panelTitle.activeBorder": "#6FC3DF" ,
"panel.dropBorder": "#6FC3DF" ,
"panelSectionHeader.border": "#6FC3DF" ,
"panelSection.border": "#6FC3DF" ,
"statusBar.border": "#6FC3DF" ,
"statusBar.noFolderBorder": "#6FC3DF" ,
"activityBar.border": "#6FC3DF" ,
"sideBar.border": "#6FC3DF" ,
"sideBarSectionHeader.border": "#6FC3DF" ,
"titleBar.border": "#6FC3DF" ,
"notificationCenter.border": "#6FC3DF" ,
}