Add Linux support (#6)

* Add linux AppImage build target
* Add ubuntu to Github Actions build matrix
* Show help text on how to open Menu, on Linux

.github/workflows/build.yml

@@ -11,8 +11,8 @@ jobs:
 
     strategy:
       matrix:
-        #os: [macos-latest, ubuntu-latest, windows-latest]
-        os: [macos-latest, windows-latest]
+        os: [macos-latest, ubuntu-latest, windows-latest]
+        #os: [macos-latest, windows-latest]
 
     steps:
       - name: Check out Git repository

electron-builder.json5

@@ -46,5 +46,17 @@
     "perMachine": false,
     "allowToChangeInstallationDirectory": true,
     "deleteAppDataOnUninstall": false
+  },
+
+  linux: {
+    synopsis: "A dedicated scratchpad for developers",
+    category: "Utility",
+  },
+  appImage: {
+    artifactName: "${productName}_${version}_${arch}.${ext}",
+  },
+  snap: {
+    artifactName: "${productName}_${version}_${arch}.${ext}",
+    publish: ["github"],
   }
 }

electron/initial-content.ts

@@ -1,8 +1,8 @@
-import { isMac, isWindows } from "./detect-platform.js"
+import { isLinux, isMac, isWindows } from "./detect-platform.js"
 
 const modChar = isMac ? "⌘" : "Ctrl"
 const altChar = isMac ? "⌥" : "Alt "
-const windowsShowMenu = isWindows ? `\n${altChar}                   Show menu` : ""
+const showMenuHelp = (isWindows || isLinux)  ? `\n${altChar}                   Show menu` : ""
 
 export const initialContent = `
 ∞∞∞text
@@ -15,7 +15,7 @@ ${modChar} + Down            Goto next block
 ${modChar} + Up              Goto previous block
 ${modChar} + A               Select all text in a note block. Press again to select the whole buffer
 ${modChar} + ⌥ + Up/Down     Add additional cursor above/below
-${altChar} + Shift + F       Format block content (works for JSON, JavaScript, HTML, CSS and Markdown)${windowsShowMenu}
+${altChar} + Shift + F       Format block content (works for JSON, JavaScript, HTML, CSS and Markdown)${showMenuHelp}
 ∞∞∞math
 This is a Math block. Here, rows are evaluated as math expressions.