Currently, if you have multiple TextBlocks all selected at once, you are able to successfully change their local colours all at once using the Colour Picker.

However, if you instead attempt to replace the colour of MultipleTextBlocks with a Resource Colour, only the last TextBlock selected as part of the multi-selection will have the Resource Colour applied.

Although this has a 100% repro rate on TextBlocks using the methods outlined in the Repro Steps, this appears to also happen in some other Elements, albeit at lower reproduction rates.

It also appears that this operation can then also result in consequently breaking the ability to multi-edit using local values set from the Colour Picker.

See attached video demonstrating applying a local colour to multiple TextBlocks vs applying a ResourceColour to multiple TextBlocks.

Repro Steps:

1) Create a new Studio Project featuring a MainPage.xaml

2) From the Resources Panel, create a new 'Color' Resource, saved to the GlobalResources dictionary and give it any colour you wish.

3) In MainPage.xaml, introduce a StackPanel Element to the Page, and insert within it x3 TextBlocks.

4) Select all of the 3 TextBlocks at once either from the Navigator or from the Stage using Ctrl+Click or the Shift+Click shortcut.

5) With all 3 TextBlocks Selected, navigate to their shared Properties panel, click on the Foreground Property, and select any colour from the Colour Picker.

Observe how the colour of all 3 TextBlocks changes in unison.

6) From within the Colour Picker, now, instead, select the swatch of the Color Resource created in Step 2).

Observe how only 1 of the 3 TextBlocks has the chosen colour applied to it.

Expected Results: Resource Colours can be multi-applied in the same way that local colours can.