Mobile: Fixes #3022: Fix issue with action button disappearing in some contexts

ReactNativeClient/lib/components/action-button.js

@@ -93,7 +93,7 @@ class ActionButtonComponent extends React.Component {
 		}
 
 		if (!buttonComps.length && !this.props.mainButton) {
-			return <ReactNativeActionButton style={{ display: 'none' }} />;
+			return null;
 		}
 
 		const mainButton = this.props.mainButton ? this.props.mainButton : {};

ReactNativeClient/lib/components/screens/notes.js

@@ -227,9 +227,12 @@ class NotesScreenComponent extends BaseScreenComponent {
 			);
 		}
 
-		const addFolderNoteButtons = this.props.selectedFolderId && this.props.selectedFolderId != Folder.conflictFolderId();
+		let buttonFolderId = this.props.selectedFolderId != Folder.conflictFolderId() ? this.props.selectedFolderId : null;
+		if (!buttonFolderId) buttonFolderId = this.props.activeFolderId;
+
+		const addFolderNoteButtons = !!buttonFolderId;
 		const thisComp = this;
-		const actionButtonComp = this.props.noteSelectionEnabled || !this.props.visible ? null : <ActionButton addFolderNoteButtons={addFolderNoteButtons} parentFolderId={this.props.selectedFolderId}></ActionButton>;
+		const actionButtonComp = this.props.noteSelectionEnabled || !this.props.visible ? null : <ActionButton addFolderNoteButtons={addFolderNoteButtons} parentFolderId={buttonFolderId}></ActionButton>;
 
 		return (
 			<View style={rootStyle}>
@@ -250,6 +253,7 @@ const NotesScreen = connect(state => {
 	return {
 		folders: state.folders,
 		tags: state.tags,
+		activeFolderId: state.settings.activeFolderId,
 		selectedFolderId: state.selectedFolderId,
 		selectedNoteIds: state.selectedNoteIds,
 		selectedTagId: state.selectedTagId,

ReactNativeClient/lib/models/Setting.js

@@ -252,7 +252,12 @@ class Setting extends BaseModel {
 
 			'sync.maxConcurrentConnections': { value: 5, type: Setting.TYPE_INT, public: true, advanced: true, section: 'sync', label: () => _('Max concurrent connections'), minimum: 1, maximum: 20, step: 1 },
 
+			// The active folder ID is guaranteed to be valid as long as there's at least one
+			// existing folder, so it is a good default in contexts where there's no currently
+			// selected folder. It corresponds in general to the currently selected folder or
+			// to the last folder that was selected.
 			activeFolderId: { value: '', type: Setting.TYPE_STRING, public: false },
+
 			firstStart: { value: true, type: Setting.TYPE_BOOL, public: false },
 			locale: {
 				value: defaultLocale(),