fix #7712 -- Shift-Enter when generating a cell is used twice

Also fixed some very minor style issues with the dialog. For example,
it is disconcerting to have everything styled as an ERROR just
because it is empty -- that's not standard behavior for a form
and just confuses users.

Author: williamstein

src/packages/frontend/jupyter/insert-cell/ai-cell-generator.tsx

@@ -513,14 +513,14 @@ export function AIGenerateCodeCell({
             <Text strong>Please wait until it is fully generated...</Text>
           ) : (
             <Text strong>
-              Cells are generated. You can now{" "}
+              You can now{" "}
               <Button
                 size="small"
                 onClick={insert}
                 type="primary"
                 disabled={querying}
               >
-                insert the {cellStr}
+                <Icon name="plus" /> insert the {cellStr}
               </Button>
               .
             </Text>
@@ -555,7 +555,7 @@ export function AIGenerateCodeCell({
             </Flex>
             <Flex flex={1}>
               <Text type="secondary">
-                Add a cell attributing the language model and the prompt.
+                Include cell describing the language model and prompt.
               </Text>
             </Flex>
           </Flex>
@@ -570,7 +570,7 @@ export function AIGenerateCodeCell({
                 setQuerying(false);
               }}
             >
-              <Icon name="arrow-left" /> Discard
+              Cancel
             </Button>
             <Button
               size="large"
@@ -626,22 +626,23 @@ export function AIGenerateCodeCell({
     const empty = prompt.trim() == "";
     return (
       <>
-        <Paragraph type={empty ? "danger" : undefined}>
-          Describe, what the new cell should do:
+        <Paragraph>
+          What do you want the new cell to do?
         </Paragraph>
         <Paragraph>
           <Input.TextArea
             ref={promptRef}
             allowClear
             autoFocus
             value={prompt}
-            status={empty ? "error" : undefined}
             onChange={(e) => {
               setPrompt(e.target.value);
             }}
             placeholder="Describe the new cell..."
             onPressEnter={(e) => {
               if (!e.shiftKey) return;
+              e.preventDefault(); // prevent the default action
+              e.stopPropagation(); // stop event propagation
               doQuery(prevCodeContents);
             }}
             autoSize={{ minRows: 2, maxRows: 6 }}