Added support for zenity dialogs in linux

src/main/kotlin/app/extensions/Shell.kt

@@ -0,0 +1,23 @@
+package app.extensions
+
+import java.util.*
+
+fun runCommand(command: String): String? {
+    return try {
+        var result: String?
+        Runtime.getRuntime().exec(command).inputStream.use { inputStream ->
+            Scanner(inputStream).useDelimiter("\\A").use { s ->
+                result = if (s.hasNext())
+                    s.next()
+                else
+                    null
+            }
+        }
+
+        result
+    } catch (ex: Exception) {
+        ex.printStackTrace()
+        null
+    }
+
+}

src/main/kotlin/app/ui/SystemDialogs.kt

@@ -1,10 +1,41 @@
+import app.AppStateManager
+import app.extensions.runCommand
 import app.git.GitManager
+import java.io.IOException
+import java.util.*
 import javax.swing.JFileChooser
 
+
 fun openRepositoryDialog(gitManager: GitManager) {
+    val os = System.getProperty("os.name")
     val appStateManager = gitManager.appStateManager
     val latestDirectoryOpened = appStateManager.latestOpenedRepositoryPath
 
+
+    if(os.lowercase() == "linux") {
+        val checkZenityInstalled = runCommand("which zenity 2>/dev/null")
+        val isZenityInstalled = !checkZenityInstalled.isNullOrEmpty()
+
+        if(isZenityInstalled) {
+            val openDirectory = runCommand(
+                "zenity --file-selection --title=\"Select your git directory\" --directory --filename=\"$latestDirectoryOpened\""
+            )?.replace("\n", "")
+
+            if(!openDirectory.isNullOrEmpty())
+                gitManager.openRepository(openDirectory)
+        } else
+            openRepositoryDialog(gitManager, latestDirectoryOpened)
+    } else {
+        openRepositoryDialog(gitManager, latestDirectoryOpened)
+    }
+
+}
+
+private fun openRepositoryDialog(
+    gitManager: GitManager,
+    latestDirectoryOpened: String
+) {
+
     val fileChooser = if (latestDirectoryOpened.isEmpty())
         JFileChooser()
     else