Explanation on failed snippet validation

Forward port of: https://git.reviewboard.kde.org/r/103904.

CCBUG: 274299
REVIEW: 110481

part/snippet/editsnippet.cpp

@@ -37,6 +37,7 @@
 #include <KTextEditor/View>
 #include <KToolInvocation>
 #include <KMessageBox>
+#include <KMessageWidget>
 
 #include "snippetstore.h"
 #include "snippet.h"
@@ -157,9 +158,15 @@ void EditSnippet::validate()
         for ( int i = 0; i < name.length(); ++i ) {
             if ( name.at(i).isSpace() ) {
                 valid = false;
+                m_ui->messageWidget->setText(i18n("Snippet name cannot contain spaces"));
+                m_ui->messageWidget->animatedShow();
                 break;
             }
         }
+        if (valid) {
+            // hide message widget if snippet does not include spaces
+            m_ui->messageWidget->animatedHide();
+        }
     }
     button(Ok)->setEnabled(valid);
     button(Apply)->setEnabled(valid);

part/snippet/editsnippet.ui

@@ -17,6 +17,19 @@
    </size>
   </property>
   <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+     <widget class="KMessageWidget" name="messageWidget">
+       <property name="visible">
+         <bool>false</bool>
+       </property>
+       <property name="closeButtonVisible">
+         <bool>false</bool>
+       </property>
+       <property name="messageType">
+           <enum>KMessageWidget::Warning</enum>
+       </property>
+     </widget>
+   </item>
    <item>
     <layout class="QFormLayout" name="formLayout">
      <property name="fieldGrowthPolicy">