I have a simple ArcGIS Pro add-in, with a button defined in the daml:
<SPAN class="token tag"><SPAN class="token tag"><SPAN class="punctuation token"><</SPAN>button</SPAN> <SPAN class="attr-name token">id</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>ProAppModule2_Button1<SPAN class="punctuation token">"</SPAN></SPAN> <SPAN class="attr-name token">caption</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>Click me<SPAN class="punctuation token">"</SPAN></SPAN> <SPAN class="attr-name token">className</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>Company.Project.Button1<SPAN class="punctuation token">"</SPAN></SPAN>
<SPAN class="attr-name token">loadOnClick</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>true<SPAN class="punctuation token">"</SPAN></SPAN>
<SPAN class="attr-name token">smallImage</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>Images\sample16.png<SPAN class="punctuation token">"</SPAN></SPAN>
<SPAN class="attr-name token">largeImage</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>Images\sample32.png<SPAN class="punctuation token">"</SPAN></SPAN>
<SPAN class="attr-name token">keytip</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>This is a tip<SPAN class="punctuation token">"</SPAN></SPAN><SPAN class="punctuation token">></SPAN></SPAN>
<SPAN class="token tag"><SPAN class="token tag"><SPAN class="punctuation token"><</SPAN>tooltip</SPAN> <SPAN class="attr-name token">heading</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>This is a heading<SPAN class="punctuation token">"</SPAN></SPAN><SPAN class="punctuation token">></SPAN></SPAN>Tooltipbody<SPAN class="token tag"><SPAN class="token tag"><SPAN class="punctuation token"><</SPAN>disabledText</SPAN> <SPAN class="punctuation token">/></SPAN></SPAN><SPAN class="token tag"><SPAN class="token tag"><SPAN class="punctuation token"></</SPAN>tooltip</SPAN><SPAN class="punctuation token">></SPAN></SPAN>
<SPAN class="token tag"><SPAN class="token tag"><SPAN class="punctuation token"></</SPAN>button</SPAN><SPAN class="punctuation token">></SPAN></SPAN><SPAN class="line-numbers-rows"><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN></SPAN>
However, inside the button class the TooltipHeading is an empty string. (Tooltip contains the text 'Tooltipbody').
What am I missing?