Fixes for Context menu tutorial (#1059)

* Small fixes for Context Menu tutorial

* Fixing Context Menu tutorial

tutorials/Context_Menu/README.md

@@ -11,6 +11,14 @@ There is out-of-the box context menu support for TextField and Selectable text.
 To enable standard context menu for a TextField you just need to put it inside DesktopMaterialTheme:
 
 ```kotlin
+import androidx.compose.desktop.DesktopMaterialTheme
+import androidx.compose.material.Text
+import androidx.compose.material.TextField
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.window.singleWindowApplication
+
 @OptIn(ExperimentalComposeUiApi::class, androidx.compose.foundation.ExperimentalFoundationApi::class)
 fun main() = singleWindowApplication(title = "Context menu") {
    DesktopMaterialTheme { //it is mandatory for Context Menu
@@ -29,6 +37,12 @@ Standard context menu for TextField contains the following items based on text s
 Enabling standard context menu for a Text component is similar - you just need to make it selectable: 
 
 ```kotlin
+import androidx.compose.desktop.DesktopMaterialTheme
+import androidx.compose.foundation.text.selection.SelectionContainer
+import androidx.compose.material.Text
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.window.singleWindowApplication
+
 @OptIn(ExperimentalComposeUiApi::class, androidx.compose.foundation.ExperimentalFoundationApi::class)
 fun main() = singleWindowApplication(title = "Context menu") {
    DesktopMaterialTheme { //it is mandatory for Context Menu
@@ -44,6 +58,22 @@ Context menu for text contains just Copy action.
 To enable additional context menu items for TextField and Text components, ContextMenuDataProvider and ContextMenuItem elements are used:
 
 ```kotlin
+import androidx.compose.desktop.DesktopMaterialTheme
+import androidx.compose.foundation.ContextMenuDataProvider
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.text.selection.SelectionContainer
+import androidx.compose.material.Text
+import androidx.compose.material.TextField
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.ContextMenuItem
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.singleWindowApplication
+
 @OptIn(ExperimentalComposeUiApi::class, androidx.compose.foundation.ExperimentalFoundationApi::class)
 fun main() = singleWindowApplication(title = "Context menu") {
    DesktopMaterialTheme { //it is mandatory for Context Menu
@@ -79,6 +109,20 @@ In this example Text/TextField context menus will be extended with two additiona
 There is a possibility to create a context menu for an arbitary application window area. This is implemented using ContextMenuArea API that is 
 similar to ContextMenuDataProvider. 
 ```kotlin
+
+import androidx.compose.desktop.DesktopMaterialTheme
+import androidx.compose.foundation.ContextMenuArea
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.width
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.ContextMenuItem
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.singleWindowApplication
+
 @OptIn(ExperimentalComposeUiApi::class, androidx.compose.foundation.ExperimentalFoundationApi::class)
 fun main() = singleWindowApplication(title = "Context menu") {
    DesktopMaterialTheme { //it is mandatory for Context Menu