Restore the CWM::RichText scroll after updating its content

library/cwm/src/lib/cwm/common_widgets.rb

@@ -365,6 +365,40 @@ class RichText < AbstractWidget
     self.widget_type = :richtext
 
     include ValueBasedWidget
+
+    # Determines if the scroll should be restored after updating the content
+    #
+    # @return [Boolean] true if the scroll should be restored; false otherwise
+    def keep_scroll?
+      false
+    end
+
+    # Updates the content
+    #
+    # Depending on #keep_scroll?, the scroll will be saved and restored.
+    #
+    # @param val [String] the new content for the widget
+    def value=(val)
+      current_vscroll = vscroll
+      super
+      self.vscroll = current_vscroll if keep_scroll?
+    end
+
+  private
+
+    # Saves the current vertical scroll
+    #
+    # @return [String] current vertical scroll value
+    def vscroll
+      Yast::UI.QueryWidget(Id(widget_id), :VScrollValue)
+    end
+
+    # Sets vertical scroll
+    #
+    # @param value [String] the new vertical scroll value
+    def vscroll=(value)
+      Yast::UI.ChangeWidget(Id(widget_id), :VScrollValue, value)
+    end
   end
 
   # Time field widget

library/cwm/test/common_widgets_test.rb

@@ -6,7 +6,6 @@
 require "cwm/rspec"
 
 describe CWM::RadioButtons do
-
   class TestRadioButtons < CWM::RadioButtons
     def label
       "Choose a number"
@@ -59,3 +58,47 @@ def hspacing
     end
   end
 end
+
+describe CWM::RichText do
+  subject { described_class.new }
+  let(:widget_id) { Id(subject.widget_id) }
+
+  describe "#value=" do
+    before do
+      allow(subject).to receive(:keep_scroll?).and_return(keep_scroll)
+      allow(Yast::UI).to receive(:ChangeWidget)
+    end
+
+    context "when set to restore the scroll" do
+      let(:keep_scroll) { true }
+
+      it "saves the scroll position" do
+        expect(Yast::UI).to receive(:QueryWidget).with(widget_id, :VScrollValue)
+
+        subject.value = "Test"
+      end
+
+      it "restores the scroll" do
+        expect(Yast::UI).to receive(:ChangeWidget).with(widget_id, :VScrollValue, anything)
+
+        subject.value = "Test"
+      end
+    end
+
+    context "when set to not restore the scroll" do
+      let(:keep_scroll) { false }
+
+      it "saves the scroll position" do
+        expect(Yast::UI).to receive(:QueryWidget).with(widget_id, :VScrollValue)
+
+        subject.value = "Test"
+      end
+
+      it "does not restore the scroll" do
+        expect(Yast::UI).to_not receive(:ChangeWidget).with(widget_id, :VScrollValue, anything)
+
+        subject.value = "Test"
+      end
+    end
+  end
+end